Below are instructions on how to install a wallpaper on your computer desktop.
If you're using a PC, just right click on the wallpaper, and select "Set as Wallpaper" on the menu.
Click and hold on the image with your mouse button. When a menu pops up, select the Save Image As or Download Image to Disk option to save the image to your hard drive. You can rename the file if you wish, but be sure to retain the .jpg extension.
System 8.5 or Higher
If you've got System 8.5 or higher: Go to the Apple menu and select the Appearance Control Panel. Click on the Desktop tab. If you already have wallpaper on your desktop click on the Remove Picture button to remove your old wallpaper. Now use the Select Picture button to select the wallpaper you just downloaded. After you have selected your wallpaper, press the Set Desktop button and close the window.