A wallpaper or background is an image (photo, drawing etc.) used as a decorative and a pictorial tool of beautification of one’s device. It is the background of a graphical user interface (GUI) on the screen of a computer, mobile
communications device or other electronic device.
Go to Personalization
click on Background to change the background/wallpaper of your Windows 10 PC. Select your favorite picture from the gallery.
You can also choose a fit for the picture.
Microsoft offers a massive and a majestic collection of Windows 10 Wallpapers on its website from where you can download them and set them in your PC.
If you wish to set any image or photograph as your desktop background, right-click on it, as you have always done, and click on Set as desktop background.
To let Windows 10 change your wallpaper automatically, select Slideshow from the dropdown menu of Background and set the desired folder with your images.