Background color of the screen can be changed by following
the followed steps :
  
1> Right click on the selected screen whose color has to be changed.
  
2> A pop up menu comes where only the "Color" menu item is enabled.
  
3> Clicking on "Color" menu item,a color chooser window comes.
  
4> Choose any color and click on "OK" button.
  
5> The background color of the selected screen gets changed to the 
selected color.