Download the wallpaper by clicking on your choice of resolution. Next, right click on the image and select "set as wallpaper" or "set as background." (TIP: To make image fill whole screen, once wallpaper is loaded, go to startmenu/settings/control panel and select background tab, then select stretch under the page display settings.)
Download the wallpaper, then drag the picture to your desktop. Go to control panels/appearance/desktop and select the picture you just downloaded.