Your junior high school offers classes in C++ programming? That's really impressive, even if at that level they won't be able to cover more than the most superficial aspects of the language.
If you've never programmed before, you should know what it is you're getting into. Programming non-trivial applications is hard, and it can take years of practice before one becomes proficient at it, not unlike learning to play a musical instrument. Don't expect to take one class to turn you into an expert, or even borderline passable, programmer. Even at the university level, Computer Science programs have a high proportion of wash-outs.
The good news is that you're at the perfect age to begin learning how to do it. You kids can be awfully clever and resourceful when you're motivated (how many creative hackers are only teens?). If I were you, I'd take the time to learn Objective-C and Cocoa alongside your school programming course, since Obj-C/Cocoa is what Mac application development is all about.
(and since I mentioned musical instruments, take some unsolicited advice and pick up some skills on one of those, if you haven't yet already; later on, it won't matter even if you're ugly, chicks will want you if you know how to play the guitar)