Okay, I know there are stickies for this, but I may have found an easier way to make the basic parts of a map, with PAINT none the less, and quite well actually.

you need to open paint, and figure out how big you want your map, and set the resolution.
make the entire thing that exact color of pink that is not there. and take the shape of your map, and make it black.
you will be editing this later. but for now save it and close.

step 2:
find a small pic, like a jpg or bmp, or gif or something, that will be how your materials will look in game. such as the differant types of dirt and concreet and steel.
you dont want them to be solid collor, right?
a small looping jpeg will work niceley.
copy it, and tile it to the resolution of your map.
do this for all the types of materials that are in your map,
(all levels of dirt, the differant types of walls)
detail comes later.

step 3. open one or 2 of the materials files for map-parts in base.rte
any will do, as long as you see all the material colors that is used for code (not how it looks in game) and make a spreadsheet of some-kind labeling which collor is which
(that hot pink is what isnt there, you need those colors)
this way you have a color picker, to get it exact.
you can also wright down the RGB

step 4. useing the line tool, in the black space, draw out the boundrys of the materials
useing the color of the apropriate material, such as dirt,
to find the boarders of each. this is to get things like the edges of walls, and where differant types of dirt separate.

step 5: fill the black spaces in with the paint-bucket, of the apropriate color.
like that F-ed up blue-green.
this way you have pink, and all those other colors.
you notice this now looks like the material file for a map. save it as such, your done with this part.
now its faster than before.

step 6.
keeping this file open, re open one of your looped material pics.
(the map-sized one, like a huge block of sand, whatever)

find a small part of it that isnt going to be in your map
(some space in the pic) and copy the color from your coler picker, paste it in, so you can select that collor in your material template.
set it as the transparancy color, and copy your entire material map, and then paste with transparancys.
the color from the material map, will be over-top of your sand, or steel or whatever,
and the sand or steel or whatever, will show through instead of the material color.

repeat this step for every material,
and now you have a slightly blockey pick, with all the materials collored in like it would be visible,
(ground anyway, hollow spots arent visible yet)
save it as a diferant file.

step 7 open your material templates (what the steel and sand and concrete look like)
and edit it in the following way.
make it darker.
pretty much can be done by makeing an identical sized pick, and filing it with a darker color of each collor and pasteing over with transparancies,
of all the colors in the file (thats why you probly wanna only use 4-8 colors, size wasnt the only reason for 8-bit)
now you have an identical pic thats about 30-45 darker
save it again, as a diferant file and do this for all your materials

if you skip this, when you destroy terrain it will just show sky behind it, instead of ruined ground or walls. if you dont care, then just dont bother with this step

step 8:
(if you opted to skip 7, you can skip part of this step, you'll know what parts)
remember all the copy and pasteing with your entire map earlyer?
where you used the materials like a cut-out?
you get to do that again ^_^
this is your back-drop for the map that your makeing now.
this will include background for rooms, such as the brain-room,
as well as what it looks like behind the ground when you blow it up.

so do all that over with the darker templates. it wont take as long as it seems.

next, draw in, over the pink, where you want something to be visible, but not actualy there
(backgrounds inother words)
draw all the detail where that is.
while your at it, move to step 9

step 9:
details
while you've got the backdrop open, add your details, lines, markings, scratches, bolts,
bullet holes, etc.
you can make a few ahead of time, and copy/paste them over.
this makes it look awsome.
when your done do the same thing to the other non-material map
(the one that is how you would see it)
add more detail.

now the last and hartest 2 parts.

step 10:
non existant material.
open your material map, and your bg texture map (not the sky one, you havent made that yet)
open the one with the details twice actualy

copy just the bright pink of the material map over to the detailed one (your not saveing)
wait, nevermind, LOL
its already there.
make your detailed map (not the BG one monocrome.
YOUR NOT SAVEING IT.
take the part that ISNT the see-through pink, and copy that. close it
open your detailed bg image (the one with the background walls and such.
and paste it over top of it, the shape of what is there.
this way you have pink, black (or whatever collor) and the detailed background of what doesnt have dirt infront of it.

make the bg walls and such one collor (your not saveing this either)

here's why.
aparently there's a collor that's in the material map, that is non-material.
open 2 files from base.rte.
you know that wall thats in some of the maps by default?
the one thats a block held up in mid air, that you can walk under that?
if you open the material for it, you have that pink, but the part you can walk through, is a differant darker pinkish-purple color, right?
thats the color for stuff thats visible that you can walk through.
make the shape of your background walls that collor, and copy it,
paste it into your material image, exactly where it is, perfectly by the pixel.

i'm not 100% sure its needed, but i'd rather be safe

you now have a map, thats perfectly ready, exept the sky, which you could just copy the old sky, and edit it, there's no material, so you can make it look like whatever you want, you could make it your wallpaper for all it maters)
now the hardest part.

step 11:
the code.
the code is for where your people are, where the computer's people are, what materials are used, where your brains are, etc.
i have no clue how to do this, but its code so its probably harder.

but if you followed my steps correctly,
(read them through once so you understand it, then used as referance)
and you had an idea in mind, and dont suck with the line-tool
then you should have a working scene in about a half an hour to an hour, that looks damn nice.

and if your a bit slow, just in case, to sum it up for the cutting and pasting,
the templates are like pieces of construction paper with doodles on it, and the material, prety much cuts out shapes of it, and pastes it together, so it looks right, and thats what your doign for most of the time, its like an episode of southpark.
so by the time your done, your map's RTE will have the sky, and then 3 images.
a material, a map (dont know the file names btw), and a bg map
the material tells the game that the map is made out of steel or concrete or rock or whatever, and where at, and the map is what it looks like to us. the bg is whats behind it,
and the sky is behind the BG, and is your real bg. this slides as you scroll through in game.

i hope this clears up any noobs going "HOW DO I MAKE L33T MAPS" and cant post about it cause there scared.

i hope this is clear enough to understand, I tried my best.
also i have an idea for a program that someone could make in there free-time if they have any.
one that would load the base.rte and the differant pics for the map, and you can place brains or troops or gold or rocks or whatever, and it would record the right points, make a text file,
and you just re-name it .ini and copy it to your map's .rte and your done.
a basic scene editor basicaly
i cant code for crap so mods from me will be slow.
if there's anything i'm good at its old-skool grafics ^_^

and now that you've read this i hope you see its not impossible to make good maps.
i expect some damned good ones now! none of this "teh computer's brain is in teh dirt, and they just attack infinatly" crap. i want real maps with thought put into them, by map designers that arent about code.
i expect something that doesnt look all 8-bit.
i expect something that uses 32-bit collor for once!
i want someone to take a few photo's of things like there lawn, and sidewalk, and abridge, and a military bunker, and photoshop it together, and make the materials match, and be detailed!.
its not hard, and if you do it right its not that time consuming, the hardest part is code, and people can explain that, its mostly X,Y axis stuffs and easy to copy and paste,
but i dont know enough YET to do it myself.
i was just diging through and figured it out, and my brain clicked.
i know how to make a scene, just not one that has any instances in it :P

Capitalize your "i"s, add more "enters", and take out all the un-meaningful details.

Compress, and synopsize.

Otherwise it looks like a fine Tut.

Its a great tutorial but you need to use grammar.

maybe add some pics or even lazier get someone else to
because i'm lazy i got bored of reading it at like step 6 so hey hopefully then it will get stikied

Holy crap, condense it a little bit. TL;DR.

Also, pix or gtfo.

Far too complicated.

Scenes are really easy in B14, this guide makes them look hard.