Ah - good choice - this is one of my favourites! I suppose you what to know how to get it on the desktop now. To get your chosen wallpaper to be set as your desktop background can be done in many ways.One way is to right click the desktop background below and then choose 'save target as...' (IE & Opera) or 'save link as...' (Firefox). Don't forget where you saved it though! Then go to wherever you set the background for you particular computer / operating system and select the image.
A different way altogether is to right click the background below, from here choose 'save image as...' or 'set as Desktop Background' or 'Set as Background'. When the time is nigh - you'll do it right. I trust you. I bet you've figured it out already. I'll button it now.
Return to wallpaper thumbnails.