Open the Settings app
Tap Wallpaper
Tap Add New Wallpaper
Choose a wallpaper from Photos, People, Photo Shuffle, or built-in options
Adjust the image if needed
Tap Add
Choose Set as Wallpaper Pair, Set as Home Screen, or Set as Lock Screen
Confirm your selection
To change an existing wallpaper, press and hold the Lock Screen
Tap Customize or the plus button
Select a new wallpaper
Tap Done