How to do it yourself?

Hi, I'm new here and I've been bouncing around the faqs and forums hoping to find this question. If it has already been answered in there and I missed it, I'm sorry. My question is simple; How does someone find/make these codes themselves? I'm kind of a "do-it-yourself" kind of person so I like to find codes for myself. Thank you.

Well, I use to do it for NES and SNES and GB and GBA and stuff. Bascially any emulator that gave you the option of looking at and editting the memory and stuff. But to be honest, I'm not looking to be recurited, I have almost no time as it is . I'm just not the type that like to bother others if I can learn to do it myself. I'll check out the chatroom this weekend, it's been a long while since I've used IRC . Thanks a bunce.