Well if you don't know C++ then you should take this time now to learn about the programming language. Once you know about the programming language then you can learn about programming robots in C++.
For learning, the best IDE in my opinion would be Microsoft Visual C++ Express 2010.
For learning resources you can find some eBooks that teach C++ or use Google. PM me if you want an eBook to read about starting in C++.
Reference of the C++ Language Library
Documentation for WPILib
I'm not knowledgeable about C++ but I know Java.