where are your variables declared?
make sure they are declared in the file main.h
class ExtObject : public CRunObject
also make sure you begin any functions you've named yourself with ExtObject::youractionnamehere(LPVAL params)
As far as learning as a beginner, and asking too many questions. ask away, nonstop, if I don't answer it means I probably haven't had time for a detailed answer yet. I and others learned alot of the basics while learning to make construct plugins. Sometimes the answer might be "read a tutorial on such and such", but if you're determined you can learn to program using construct and it's SDK. this is where I started learning to program in earnest, and I'm confident that if I had just been learning off regular, less exciting examples in tutorials dealing with text, and ugly command line stuff, I wouldn't haven't learned nearly as fast as I have.
as far as this question
I would say it's a good idea to google local and global variables, it's very easy to find them on google. also Class Inheritance. It might not make alot of sense to begin with, but it'll give you a better idea of the forces at work that are stopping your programs from compiling. if you see other words in the explanations that are mysterious to you, look those up, too. Understanding the things that cause errors that don't have to do with your actual task are good to get out of the way early on.