Objects and Classes?

First, I'm more of a quick learning hack than a developer. I have some code with a few functions that I've written. I have moved a good part of this to a class and have updated the code to define an object based on this class and do its stuff. I feel that I understand objects/classes and how to code and use them, but what I'm having trouble with is the logic of building the class. Why did I build the class (just seemed like the thing to do)? Should the class be most of my app so that it can be accessed by others? This is more of a high-level app development question. Does anyone have good info or methodology on when to use a class and what components make sense to include in the class? How many classes? I could send my code to anyone who is a guru in this that could just give me some high-level advice. Thanks! Shawn (Just learning)