help with modding games

Can anyone please help on modding my own games for 360 rgh i wish to learn how to mod a couple of games my self can anyone give a list on what best programs to use i want make my own for learning purposes e.g gta5,halo wars,c&c tiberium wars and i wont be using online so that should make it easier not yet anyways

 

HxD editor is a good program to look through files of the games and change stuff.

 

if youre just starting out use 360 revolution or save editors mate