how to run game trainers

[ineedhelp]

hello can someone plz help im trying to find out how to use trainers i download the trainer and it says cant find game when i try to run it how do you get this thing started pretend your talking to a moron lol well anyways i dont know how to do this hope someone can help say for example game vietnam ho chi minh how do i get trainer to work from start to finish on how to set it up thanks