When you open your micro SD cards first folder, you see a folder called EDGE. Open that. In that folder there may be a folder called skins. if there isn't a folder like that, create it. Then put the folder called "mario" with all files in it there. Then get the reader out of the computer. Plug the iEDGE in the DS/DSi (with micro sd card ofcourse ) Select the last option (the most right option). Go to "Skin" (or something like that, I have not touched my EDGE in ages) and press right. Now select "Back to main menu" (something like that). The skin should have changed.