I'm really new one over here and I really want to learn how to mod Stuff in Cortex Command. I don't know where to start. I already tried to make my on character, but it didn't work at all. So then I knew I need help. So if somebody can teach me or give a hint, thanx in advance.

Start with something small. Edit things rather than try to go for something new right off the bat. Once you can easily tell what your edit will do, try making your own grenade or gun by copying something from the basegame. Once you're adept at doing that, then you'll be able to branch out and make a whole pack of guns, or work on actors.
Start small and work your way up.

Yeah thats true.
I started just a few days ago with informatic basics.
And looked through some tutorials.
These are good ones:

First Gun(I started with this):
http://www.moddb.com/mods/the-crowguard ... dification

When you don't know what something is doing:
viewtopic.php?f=1&t=19887

A few other tutorials:
viewtopic.php?f=1&t=16824

Pixel Basics(Helpful for shading etc.):
viewtopic.php?f=1&t=18005

Also the wiki is very helpful.

When you are a little bit better and you can create a new gun
this should be helpful:
viewtopic.php?f=1&t=19092

I hope this will help you.

The-Blog

Thnx really much guys. This really helped! =)