Instructions
Lift open the "SD Card" flap on the side of the Nintendo DSi. Press down gently on the SD card, and then pull it out.
Slide the SD card into your computer's card reader. Some computers use an integrated card reader, but external readers may be purchased if yours doesn't have one. Alternatively, if you have a device that connects to your computer and accepts SD cards, including a digital camera, it can be used as a card reader.
Wait a few seconds. A sound is emitted, letting you know the card was read. Access the card by clicking "Start" and then "Computer."
Double-click the SD card icon. This is found under "Devices with Removable Storage." All of the files on the card are shown. If you want to add new files, just drag and drop them into this window.
Place the SD card back into the Nintendo DSi card slot when you are finished.