Once you’ve downloaded a “wallpaper” image, you can either set your desktop background (“wallpaper”) directly, or save the JPEG file to your hard disk. Setting the wallpaper directly is easiest, but it has the disadvantage that you’ll lose the image if you later change the wallpaper. You’ll have to download it from the Web site if you want it again. If you save the JPEG file, it will still be there if you change the wallpaper, and you can do other things with the image.

Note: Be aware that a wallpaper image ties up a chunk of memory equal to three times the image dimensions (one byte for each color). So a 1024x768 desktop background occupies somewhat more than two megabytes of memory, and a 1680x1050 wide-screen image uses 5.3 megabytes. If your computer has less than 256 megabytes of RAM, you really shouldn’t be using a large image as wallpaper.

For Windows

To set the wallpaper in Microsoft Internet Explorer, move the mouse pointer over the image and right click. Choose “Set as Wallpaper” from the menu. In Firefox, choose “Set as Desktop Background.” In Opera 5, 6, or 7, right-click and choose “Use image as”; then select “Desktop background”. In Opera 8 or 9, choose “Use Image on Desktop.”

If you’re using a screen resolution higher than 1024x768 (or 1680x1050 for the “wide screen” images), open the Windows Control Panel, choose “Display Properties,” and select “center” rather than “tile”. The image will be centered on the screen, with the borders in the background color of your display scheme. Some versions of Windows include the option of expanding the image to fill the screen.

To save the image file in Microsoft Internet Explorer or Firefox, move the mouse pointer over the image and right click. Choose “Save image as” or “Save file”. Then select the desktop or the folder where you want to save the JPEG file. In Opera, right-click and choose “Save image”. You can enter the location of the saved file into your browser, and then set the wallpaper as described above.

For Macintosh OS X

To set the wallpaper, move the mouse pointer over the image, click, and hold down the button to drag the image (as a miniature icon) to the desktop. Then click on System Preferences and drag the image icon from the desktop into the “well.”

To save the image file, move the mouse pointer over the image, click, and hold down the button to drag the image (as a miniature icon) to the desktop, or to the folder where you want to save it. You can enter the location of the saved file into your browser, and then set the wallpaper as described above.