N64 Cheats are made up of Gameshark and Action Replay Codes GS = NTSC and AR = PAL but for all cheat related things you can either visit PJ64 Cheats Website on the Cheat Help section or in your root folder the cheat.chm file that came with PJ64 SP1.
Please read before posting as both the site and Cheat.chm also have a cheats FAQ.