How do I change the background in Windows 10?
Changing the background in Windows 10
To change the background go to Start > Settings > Personalization > Background
Under Background, you can choose between
Picture is a single image you'd like to select from the preinstalled picture, or you can click on browse to select a personal image.
Solid color presents you with a color palette to choose the color you want.
Slideshow allows you to select a folder with pictures in it. You'll have to browse to tell it exactly were the folder is.
Then you can choose how often to change the picture with the "Change picture every" option:
Then you can choose "Choose a fit"