How to Change Your PC Background From Blackby Steve McDonnell
Just as you might hang wallpaper at home to change the color of a wall from black to something different, you can change your PC background from black to a solid color, design or a picture in Windows 7 and earlier. In Windows 8 and later, you can apply a theme to change the desktop background, and you can also change the background color of the Start screen, which is also used as the background for the Charms and the Sign-In screens.
Windows 7 and Earlier
Click "Start | Control Panel | Appearance and Personalization | Personalization | Desktop Background."
Select one of the Windows-standard background images by double-clicking it. Click in the Picture Location list box and select "Solid Colors" to choose a solid color replacement for the black background. Click "Browse..." and select a picture to use as your desktop background.
Click "Save Settings" to change your PC background from black to the background you selected.
Swipe in from the right, choose "Search," type "Personalization" and select "Settings."
Select "Personalization," tap the theme you want to use on your desktop and select "Desktop Background" to apply the theme.
Swipe in from the right, choose "Settings" and select "Change PC Settings." Choose "Personalize" and select "Start Screen."
Click on the different colors to change the background color of the Start screen, Charms and Sign-In screens.