Select your favorite picture in the desired format, save the image on your hard drive, and then make it your desktop image.
Note : if a format below is highlighted, it is the best one to use for your screen.
4:3 1600x1200 1280x1024 1024x768
16:9 1920x1080 1600x900 1366x768
16:10 1920x1200 1680x1050 1280x800