Newbie Questions

Hey! well its kinda simple. My question is, How do you guys use these codes I see everyone sharing?

like, you download a program? (if so, which one/s)
I've been here for a while but never actually atempted to use these codes, trainers or whatever because, well.. I just havent tried it... idk why.

SO yeah, just that... Do you need specific software? any shareable links?

cheat engine