Custom Character help

Can somebody please explain to me how to edit a character? I just found the game recently and am completely new to the world of programming. I need help with which utility is the easiest to use for beginners and how to load the character file I want to edit. And it would be helpful to know if any configuration files are required and where I can get them and how to use them

A very useful source in reference to editing characters (and levels, and well... most everything else) would be the SRB2wiki. In case you don't already know about it, here it is:
http://wiki.srb2.org/wiki/Main_Page
Specifically, information about character editing can be found here:
http://wiki.srb2.org/wiki/Character_WAD
Though the wiki can sometimes lack in the area of specifics, so if you have any further questions that the wiki doesn't cover, you can always come back here and ask.