Its pretty simple, You have a dongle (acsesskey) which goes in memory slot 1 (mine was really tight) and you have a Disc which you have to boot up to. When you get to the main menu you can either activate existing codes or you can add your own codes which can be found on Game Sharks website. after you enable a code you will be asked to insert the game disc and press x, at which point the game will start with your cheat code activated. you have to boot off of the game shark every time if you want a code to work. in the case of GT3 to activate the ten trillion credits code , you only have to boot off of game shark once since you can save to your memory card the credits that you activate with the code. Hope that makes sense.