To add a new image to your computer's desktop. Click on the thumbnail that you like. On the next page, right click on the image and select "set as desktop background" or "set as wallpaper". That will put the image from the web site to your windows desktop background.

If the image does not look as good as it did in your browser, windows has stretched it. Right click on your desktop, goto Properties, Desktop, Position and select "Center". Click "OK" and that's it. Enjoy your new wallpaper.