Go to Settings > Wallpaper > Choose a New Wallpaper.
Select a wallpaper from Apple Wallpaper or your Photos.
After you choose a wallpaper, you might need to move or scale it to fit your screen. Some wallpapers and photos might let you select between Still, Perspective, or Live Photo. Learn more.
Choose from the Set options (Set Lock Screen, Set Home Screen, or Set Both).
Press and hold your finger on a clear area of the home screen for a moment.
Tap Set wallpaper on the pop-up window that appears
Tap Home screen, Lock screen, or Home and lock screen as desired
Tap your wallpaper source. Gallery will let you look through your entire library of images, including camera, saved pictures, and screenshots. Live wallpapers are animated and interactive. Wallpapers will present the preloaded wallpaper options.
When picking from the gallery, set the appropriate cropping by tapping and dragging the boxes.The outlines show how much of the image will be visible when the phone is held upright or sideways.
Tap Done in the top-right when you’re happy with the crop scheme.