How to change desktop background image (wallpaper) in Ubuntu?
To set/change the desktop background image, follow the steps given below.
Step 1: Press Windows key in the keyboard to switch to the ubuntu desktop and in the search box type "System settings". Hit enter key.
Step 2: System Settings window opens, select Background icon under Personal.
Step 3: In the resulting pop-up, select Background.
Step 4: Click the required image under Wallpapers, Pictures or Colors and click Select.
The selected image will be set as the desktop wallpaper as given in the image below.