Instructions
Insert your GameShark disc into the PlayStation.
Enter the game title you wish to apply cheats to and then press "Right" on the D-Pad. This will bring up the "Add New Cheats" option.
Enter a description for the cheat and then press "Right" on the D-Pad. This will bring up the "Add New Code" option.
Enter your cheat code. Repeat this process for any other cheat codes you have.
Press the "Start" button and then select "Start Game With Cheats."
Remove the GameShark disc and replace it with your desired game when the system prompts you to do so. You can now begin a new game with the cheats you entered.