Instructions
Switch the power button to the "off" position on the N64.
Press the Game Shark cartridge into the top of the N64, in the slot where the game usually goes, then press the game into the top of the GameShark.
Switch the power button to the "on" position and wait a few seconds for the GameShark to load.
Press the arrows on the game controller to navigate down to "Select Cheat Codes" on the menu and press "A" on the controller. Scroll through and find the game you're playing, then press "A" to select the game and load any available cheat codes.
Press "B" on the controller to return to the previous screen. Scroll down to "Start Game" to begin gameplay.