If you already know C++ fairly well, check out the book Programming Role Playing Games with DirectX. Even if you don't want to use DirectX, you can learn a lot about making an RPG in general.
Although if you don't know C++ yet, I would suggest staying away from making an RPG (or any type of game for that matter) until you're comfortable with the language.
Accelerated C++ or C++ Primer are both highly recommended books for beginners. If you don't want to buy a book, check out the free online book
Teach Yourself C++ in 21 Days.