Step 1: Go to Settings > Wallpaper to the Wallpaper settings.
Step 2: Tap Choose a New Wallpaper at the top of the Wallpaper settings.
Step 3: Browse the wallpaper categories like Stills, Live, etc.
Step 4: Tap a wallpaper image you like to open it at full screen.
Step 5: Pinch and drag to position and zoom the wallpaper how you like.
Step 6: Tap Set to confirm and set the wallpaper on your Home Screen and Lock Screen.