Use the pull-down menus below the thumbnail images to select the image size that corresponds to the resolution of your monitor.

Windows users: To check your resolution, right click your desktop and select "Properties". Select the "Settings" tab from the window that appears. Your current resolution setting appears in the bottom right corner. Upon selecting the Wallpaper style and size you want, right click on the image that appears in the window and choose 'set as wallpaper' from the pull-down menu.

Mac users: Upon selecting the Wallpaper style and size you want, drag the image from the browser window to your desktop. Once there you can move it to your Hard Drive or Documents folder if you choose. Next, open the "Appearance" Control Panel, click on the tab marked "Desktop" and choose "Place Picture".