Point
to the top/bottom right side of your screen with your mouse or swipe in from
the right edge of the screen with your finger if your computer is touch
enabled.
select the gear (Settings)
icon
select Change PC Settings
Select a background from
the standard backgrounds under Lock Screen.
If you would like to use a picture from your library as a
background, select the Browse button at the bottom of the Lock Screen section,
select the picture for your background, and then select the Choose picture button at the bottom right of the screen.
