i forget exactly where, but somewhere on the front of the RC (take care, this is the ROBOT CONTORLLER, not the OI (Operator Interface), there is a little jumper, like on a IDE Hard Drive/CD/DVD-ROM (hey, best example that I can think of, and it's the same idea). One setting is marked to "Default" the other to "User". When set to "Default" the RC will run the default code (it's someewhere at
www.innovationfirst.com/FIRSTrobotics). When set to "User" the user can download and run PBASIC programs on the RC. As I said before, the switch is on the front of the RC, i believe on the bottom in the middle.
If you have any other questions, feel free to ask.
<EDIT>I had assumed you were using the 2002 RC, but if that is not the case, i'm not sure where the switch is, although the same idea should hold true (set to user to download and run your own programs).</EDIT>