Well, first you should decide if your going to use EasyC or normal C/MPLab.
If your going to EasyC then making a post in the easyc forum would be a good place to start. If your doing normal C then you can either go on some online websites that help teach you C, like
http://cplus.about.com/od/learningc/...rialprelim.htm but then you'd still need info on the specifics of programming for the robot. There are a bunch of papers on this that will help walk you through it, just hit CD-Media up at the top of the site and click search under Papers and just type like programming in there.
Of course if you have any specific problems or questions then just post them.