Instructions
Insert your SD card into your DSi's SD card slot. The slot is located on the left side of the device.
Power on the DSi and select "Settings" from the system menu.
Tap "Data Management" then select "SD Card."
Highlight any DSi games you wish to play or copy to your DSi, then select "Copy." This will copy the game to the DSi's internal memory. The game can be played by highlighting it and pressing "A" from the system menu.