Open the Settings app
Tap Wallpaper
Tap Add New Wallpaper
Choose a wallpaper from Photos, People, Photo Shuffle, or the default options
Adjust the image by moving or zooming it
Tap Add
Choose Set as Wallpaper Pair, Set as Home Screen, or Set as Lock Screen
Confirm your choice
Alternatively, open the Photos app
Select a photo
Tap the Share button
Tap Use as Wallpaper
Adjust the image
Tap Add
Choose where to set it
Confirm your choice