Writing Games and Programming Games are 2 different subjects that go side by side. While skipping simple Games such as Tic-Tac-Toe and jumping to a RPG is a leap, it is also a choice in doing something that might keep you motivated. Using RPG Maker is along the lines of writing a game, where you enter in all the rules and date that would make your ideal RPG game work while using someone else's programming skills to make it happen. That would be like telling Tom Clancy your War/Conflict/Spy story and having him writing it. ( Albeit at this point he would be a true ghost writer. )
If you already know C++ and you want to do Game Programming ? Your next step is to decide 2D or 3D and Pick up a book focusing on those Game programming subjects.
I personally think a 2D book focuses more on the Game Programming side of things and the 3D books focuses more on the Graphical Rendering of 3D Objects.
Check Out Amazon.com or BarnesandNoble.com for titles like Game Programming For Teens, Game Programming : All in One, 3D Game Programming. Be Careful in selecting your title, Not all books use C++, Some use Visual Basic, TorGue or some other language.
Now on to writing your own Game. Most of your programming is going to involve non-graphical functions, Start by learning those. Build a console text-based game, even start with your RPG. All of your cout statements will eventually convert over to your graphical Rendering Functions.
My First Game was a Text based American Football Game. I created Data Cards for the Players, Rolled a few Dice, crossed the Dice Roll with the Data Elements, Referenced a Game Play Chart, Moved the ball if needed, Tracked Field Positions, Updated Downs, Scored, Tracked Time and so on.
I built my game 1 Function at a time. Each Function was Just Named Above.
Good Luck and Happy Programming