If you have a PC using Windows:

1.) Click on the image or title beneath the image below;
2.) When the image appears in the new window, right click on it;
3.) When the menu appears, click the "Save as background" instruction.

If you have a Mac using OS 8 & Mac OS 9: 

1.) Save the wallpaper image above to your desktop or hard drive.
2.) The desktop appearance prefences panel is accessed differently between Mac OS 8 and Mac OS 9. For Mac OS 8 go to the Apple menu, select "Control Panel" followed by "Desktop Pictures." For Mac OS 9 go to the Apple menu, select "Control Panel" followed by "Appearance." Of the five tabbed sections in this "Appearance" window choose "Desktop." Drag the image from your desktop/hard drive to the desktop pictures preview window. Select "Tile on Screen" (Mac OS 8) from the "Position" pop-up menu.
3.) Click "Set Desktop."

If you have a Mac using OS X: 

1.) Holding Ctrl and clicking the image simultaneously, choose "Download Image to Disk."
2.) Save the image to your hard drive, preferably in the "Library | Desktop Pictures" folder.
3.) From the Finder menu choose "Preferences."
4.) In the "Preferences" window, click "Select Picture" and navigate, using the file explorer that opens for you, to your wallpaper image
5.) Click "Choose" to confirm your choice.