Re: explaination on AFMotor.h and AFMotor.cpp
This will sound rude, but most code/hardware hackers will translate that kind of request to, "someone else do my thinking for me."
More generally we can't give you meaningful answers because we don't know anything about you, your project, or your reasons for needing to understand the code. Should we assume you understand C and the Arduino environment, or would we need to teach you the language before we can explain the code itself?
Try again, but start by telling us what you're doing, how much you already know, why you need to understand the code instead of just using the interface, what you've managed to figure out on your own, and what -- specifically -- has stumped you.
Without that kind of detail, the best we can say (and about all we will say) is, "go read the code."
When you void a product warranty, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.