I think you need to learn how C++ works first. I also recommend learning ASM as that helps out so much. Codecaves are simple, coding them is a bit trickier, however kornman has made it so simple to implement, its fantastic.

You need to create a hook, and then assign it a method. The method will run when the initial hook code runs. You might need to replace the ASM code in your method but thats easy. Then you add in your hokey pokey code that does what you want it do, and bingo.

I've simplified it a bit but thats pretty much it. I understand your new to C++, and I admire you for trying to use OS, more people should be using it, but please dont insult experienced members knowledge