Hey dotbran!
I myself didn't know a line of code when I started and I can tell you from experience that FIRST makes it very easy to learn C++ in a painless way! Here are a few helpful links that can get you started!
http://first.wpi.edu/Images/CMS/Firs...ming_Guide.pdf
The link above will take you to the FIRST guide to C++. It is very useful and gives you the idea of what you can do to pretty much make anything work! This guide covers drive functions, basics of working the camera, and lots of other goodiness!
http://users.wpi.edu/~bamiller/WPILib/WPILib.pdf
This link will give you the library of the functions you will need to use. So, the first link tells you how and this link elaborates!
http://www.cplusplus.com/doc/tutorial/
If you are interested in learning C++ outside of the FIRST applications, take a look at the link above. It explains the ins and outs of the language and is very popular among beginners ( at least I like it).
If you have any questions, feel free to pm me! GOOD LUCK!
Ps. Take a look at the Windriver software! It has sample codes that you can use as a base for your robot code. Check out the "Simple Template"!