DROID MINI / DROID ULTRA / DROID MAXX by MOTOROLA - Set Wallpaper
From a home screen, select Apps (located at the bottom).
From the Apps tab, select Settings.
Select one of the following:
Select the desired wallpaper image then select Set wallpaper (located at the bottom). If selecting a photo from the Gallery, select the appropriate album, select the photo and position the crop frame as desired then select OK (located in the upper right).