Please note that the indy art and wallpaper galleries are for artworks you have drawn or created yourself. You are not allowed to add images you found from other sites in these galleries.
The scans gallery is for official images, which may or may not have been found on other sites.
The MT policy (in the support section, or linked at the bottom of every page) has more details on what is and is not allowed in the various galleries and is recommended reading for all new members.