STEPS
TOOLS
right click anywhere on the desktop.
On the pop-up menu click on personalize.
Click on Desktop Background.
Pic the new background and select it.
Click on save changes button.
Click on the red X at the top right corner to close the window.
1.0 Windows 7 Operating System

How to change your desktop background

By right clicking on your desktop and follow the guide, you can change your Desktop Background.