No, PocketFrog is a library that allows you to make easy PPC programs using C++. Look at the PocketFrog forum here in pm, and you'll find out.
To actually learn C, I reccommend Practical C Programming, the famous "cow" book. I'm not too sure about C++; I just learned using the online Wrox Press tutorial that came with VC++ 6, but then I probably don't know anything about C++...
But yeah, I reccommend that you get a book. Books are MUCH better than online tutorials. Also, if you're in school, then you might want to take a C/C++ class if your school offers one. I took one, and it helped me understand some things a bit better. If you want to use a tutorial, though, just Google arround for "C++ tutorial". Just don't rely only on that.
And yes, PPC programming is generally similar to PC programming. Both are in C++ (obviously) and both use the Win32 API, with only slight differences, which generally means programs are easily portable. However, for making games, direct screen access is generally needed, and that's where things differ. PPC games use GAPI and PC games use DirectX (generally, of course) and so there will be some difference. Simple programs should be the same though.