[heavensentinel]

You're going to want to search existing threads for more elaboration on this...

But basically, you need to move the wallpaper of your choice (sized 320x230 and named "wallpaper.jpg") to the "gfx" directory in your Touch's program files directory. (/Program Files/S2U2/gfx/"

You will need to confirm the file to be overwritten.

You can do this using your PC to copy said wallpaper to your device, or you can use a file explorer to do the same.

Hope this helps!