you can do a lot with paint it just takes a crazy amount of time and in someways is very unforgiving
if you ment a background for a sig then heres a few good tutorials
http://www.youtube.com/watch?v=O2WG-iKBNYI (this one is very basic dosn't take into consideration things like the light source etc but is slow and gets the basics across, once you've experimented with the basics a bit in whatever software ur using you can move on
here's a good tutorial at mid level its a lil more indepth and has very good links for stuff in the description, basic idea behind the background of your sig is to set the feel/scheeme of the sig, id sugest starting with a block colour that you like then just mess around with effects and brushes on it add your render at the end and you got a sig (admitedly its not going to be genious but its a start and it'll get you 2 grips with the software
as 4 c4d's i havent a clue they appear to be like a texture mask something that adds shape to a image its placed over but thats just a guess google its ass and find out