Windows Users: Right-click it and choose Set as Background or Set as Wallpaper. Mac OS X Users: Drag it onto your desktop, go to System Preferences, go to the Desktop icons, click the Collection drop-down and Choose Folder to find the new wallpaper on your computer. Mac OS 9 Users: Drag it onto your desktop, go to Control Panel and choose Appearance, click Set Desktop and choose the new wallpaper that you just downloaded.