We've shown previously how to get started with GPU debugging in Visual Studio 2012. If you read that post you know the simple steps required to hit a breakpoint in restrict(amp) code.
Next you'll want to learn about the actual parallel and GPU debugging features, and for that I recommend the 15-minute screencast giving you a taste of that experience in Visual Studio 2012 (and that includes the free Express versions!). Check it out:
Feedback and questions are, as usual, welcome below or in our MSDN forum.