Let's see if this option may work for you? Go into 'Settings' -> 'Brightness & Wallpaper' - there select the '>' option on the wallpaper menu (several items may already be present). Once selected, the right panel should give you two choices: 1) Wallpaper (which are some default images) and 2) Photo App choices; if you want to use your own wallpaper, then simply upload it to the Photo app and make a choice. Good luck and let us know if this works for you!