Things You'll Need
Instructions
Turn off your DS by sliding the power button up once. Remove the R4DS from "Slot 1" on the top of the DS.
Remove the micro SD card from the R4DS and place it in your micro SD card adapter on your PC. The contents of the disk automatically appear in a new window on most systems. If it doesn't appear, it can be accessed through the "My Computer" folder in Windows and will appear as a disk icon on Mac OSX and Linux computers.
Open the folder labeled "_system" on the micro SD card.
Double-click on the NDSTheme of your choice to unzip it. NDSThemes are packed using the ZIP file format, which most modern operating systems can unzip natively. If you are running an older system, you may need to download an archiving program like 7-Zip, WinRAR or WinZIP. Once you have double-clicked the file, a window appears displaying the contents of the archive.
Copy the four images inside the NDSTheme over to the "_system" folder on the micro SD card. These four images have the following names:
logo.bmp
icons.bmp
bckgrd_1.bmp
bckgrd_2.bmp
Remove the micro SD card from the computer and place it in your R4DS.
Place the R4DS inside "Slot 1" on your DS and turn the power on. The R4DS operating system loads and will have a whole new look.