For PC Users:
1. Right-click on the wallpaper and select "Set as Wallpaper"
2. If the image doesn't fill your screen, then right-click on your desktop, select "Properties," then "Tile"

For Users of Mac OS 8.0 to 9.1:
1. Place your cursor over the image, then click and hold
2. In the pop-up menu, choose "Copy This Image"
3. While holding the "Control" key, place your cursor over the desktop and click
4. Choose "Change Desktop Background..."
5. Press "Command" + "V" then click "Set Desktop"

For Users of Mac OS 10:
1. Place your cursor over the image, then click and hold
2. In the pop-up menu, choose "Download Image to Disk" and save the image to your hard drive
3. In the Apple menu, click on "Finder," then "Preferences"
4. Click "Select Picture..." and locate the saved image