On a PC:
When the picture has loaded completely, right-click on it, then choose Set as Wallpaper (or Background) from the pop-up menu. You can also right-click to save the picture to disk, then display it as described in the next section. If you choose Set as Background (or Wallpaper), the full-size image will normally appear on your desktop, even when it is shown smaller than actual size, as it is on our download pages.
On a Mac:
With a recent version of Safari (3 and above), when the picture has loaded completely, you can control-click on the picture, then choose "Use Image as Desktop Picture." To save the picture, you can choose "Save Image As...," then display it as described in the next section.