legosa

I understand that AX,EAX, ect...are memory addresses. But...just how do you know, what memory address is for what? And, how do you discover more memory addresses?

ZenMasterJG

EAX, EBX, ECX, EDX, EBP, ESP, ESI, and EDI are all "general purpose" 32-bit registers. AX, BX, CX and DX are the lower 16 bits of EAX, EBX, etc, etc.
Just as AX is the lower 16 bits of EAX, AH is the upper 8 bits of AX, and AL is the lower 8 bits of AH.

EBP, ESP, ESI, and EDI can be subdivided like this too, but only the lower 16 bits, with BP, SP, SI, DI (theres no access for the upper/lower 8 bits for these registers like there is for EAX & friends.)

Is there a book or tutorial you're using to learn assembly? I'm sure this is all covered in detail somewhere in there.

Oh, while ESI, EDI, ESP, and EBP are "general purpose" registers, they have specialized uses and probably shouldn't actually be used like EAX, EBX, etc.
ESP addresses data on the stack, so don't use it for anything else.
ESI and EDI are the extended source index and extended destination index registers.
EBP is the extended frame pointer register.

Theres a bunch of others for advanced stuff, but the above is kinda like "Basic Registers 101"