first, go to My Profile and under Competition Sign Up select Game Developement. Then select Compete > Game Development, and on the right side there should now be a pink button that says Create Team or something like that.
as for resources, you can download XNA and C# Express Edition from here:
http://creators.xna.com/en-US/downloads
until they post up the software downloads where you can get Visual Studio Professional (which may take a while), just practice with the Express Edition unless you have easy access to the Dreamspark website (if your school isn't listed you have to go through all this JourneyEd.com stuff that's a real pain to verify that you go to the school you say you go to).