Instructions
Search for Gameshark codes online. The official Gameshark site has a listing of codes for different gaming systems. Find the game codes for Gameboy Advance.
Start your game. Go to the "File" section in the menu folder and click the "Open" option. This should take you to a listing of your gaming ROMs. If you don't have any Visual Boy Advance ROMs, you will have to download them from a site like Gameboy Advance Roms.
Click on the "Cheats" section of the gaming menu. This will bring up a list of cheats and cheat programs. Select the "Gameshark" button. A small window will pop up.
Enter your Gameshark codes in this window. This entails filling in the "Description" and "Code" sections. The "Description" lets you know what cheat you are entering while the "Code" is the actual number and letter combination that activates the cheat. Press OK when you have entered your codes.
Go to the "File" menu and click the "Restart" button. This is necessary to activate the codes.