How do you have Mk7 on your wii u?

thats the WaraWara plaza it shows on your wiiu home menu on tv usually it shows any game community on here even 3ds games

plz tell me how to chance your wii U's background,ive been struggling to do it,maybe you could help me? i'll DM you a photo of my main menu because maybe you would see the problem from there and DM me how to fix it,if you want to,(no pressure).