Instructions
Add Game Titles
Select the "Select Cheat Codes" option to enter the "Select Cheat Codes" menu.
Highlight the "New Game" option found at the top of the list. Press the "A" button to select it.
Select "New Game" from the "New Game Edit" screen. When the text entry box appears, enter the name of the new game (use the directional pad to highlight different letters and use the "A" button to select a letter).
Press the "B" button after entering in the name of the new game, then press the "A" button to save the changes you made.
Add Codes
Choose the "Select Cheat Codes" option to enter the "Select Cheat Codes" menu, then highlight and select the game you just added.
Choose the "New Code" option. Select "New Code Description" to bring up a text box. Enter a description for the code (such as "Infinite Lives" for a code that gives you infinite lives).
Press the "B" button after you have entered the code description, then highlight and select the "Code Entry" box. Enter the appropriate code, then press the "B" button. Press the "A" button to save the new code.