How can I create a hack?

Ok guys
I have the same question. I know c++ but yesterday i tried to understand aimbot sources for Battlerite and there is some moment i cant understand.
For example: memory read and write to the process of the game - obviously we need to do this when hack the game, but how should i know what exactly to read and write in the process? Maybe there is a manual for such situations?

Sorry for my english
Just want to make some moments clear

Learn C++ by programming small, cool programs. Work your way up from that and go to reading guides in places like here.