Samsung GalaxySIII User Manual page 73

To change the current Lock screen wallpaper:
1. Navigate to any screen, touch and hold an empty area
of the screen, and tap Lock screen.
– or –
Press
Wallpaper Lock screen.
2. Select a Wallpaper type:
• Tap Gallery to select from a user image stored in the camera
image gallery, crop the image, and tap Done.
• Tap Wallpaper, scroll through the images, tap a wallpaper
image, then tap Set wallpaper.
and then tap Settings
Understanding Your Device 67