Cheats
To access the Cheat Window, press Start > Cheats or Touch the Cheat button on the .NDS properties screen.
[edit]How to Enable Cheats
Begin by enabling cheats. The cheat patch needs to be enabled or else the cheats will not work. The patch can be enabled globally at Start > System Options > Default Patch Options. Cheats can also be disabled/enabled on a per-Rom basis by viewing the properties of the ROM and clicking on the Rom Settings button.
Open the Cheat Window (as stated above) and you will see cheat codes that are not sorted into folders first, followed by folders, in a list. Folders can be expanded by pressing the A button while it is highlighted or by clicking on the folder. Pressing the A button or clicking on a cheat while a it is highlighted will enable that cheat, or disable it if it is already enabled. Pressing the Start or Select button will save and exit, something you must do.