You're not allowed to submit wallpapers you did not create; this includes wallpapers you find on the Internet. Doing so is considered ripping, which is not allowed by the MT Policy.

Since you're new here, I won't give you an official warning yet. But please read the policy to see what you can and cannot submit. If you continue to rip, I will have to give you an official warning. Note that 2 warnings will get you restricted, and 3 warnings means you'll be banned.