Here are few wallpapers for your iPad.
Click to the Wallpaper size, the photo will open in a separate window.
Hold the image with your finger. Press Save. Go to Settings, then Brightness and Wallpaper, then choose "Saved Photos". Pick a photo from there and in the right top corner select which screen you want it to appear on. Of course, you can choose any other wallpaper from this site. It works the same way.