PC users: Click on the link that corresponds to your screen resolution. Right-click on the large image and choose "Set as wallpaper" from the menu.
Mac users: Click on the link that corresponds to your screen resolution. Click and hold on the large image until a menu appears. Choose "Download image" or "Save image as" and save the image to your hard drive. Go to System Preferences and choose "Desktop" and select the JPG file you downloaded.