Either you want to learn reverse engineering and memory manipulation/hooking, or you want to learn sockets and cryptography; all depending on whether you want to create a memory-based bot or a proxy bot.
There's no specific guide on how to do it, mostly because it can differ from patch to patch, server to server etc. all depending on cryptography, compiled/packed executable, anti-hacks, anti-debugging etc.
Knowing a programming language is the least you need to know, but there's so many concepts out of the range of just programming languages.