Ah - good choice - this is one of my favourites! I suppose you what to know how to get it on the desktop now. There are a number of ways to set the chosen wallpaper as your desktop wallpaper / background. You can either right click the background below and then choose 'save target as...' (IE & Opera) or 'save link as...' (Firefox). If you do this - remember where you saved it! Next you need to go to where your computer's operating system display settings and set the image as your background / wallpaper.
Alternatively, when the full screen image is up, right click it and select 'save image as...' or 'set as Desktop Background' or 'Set as Background'. When the time is nigh - you'll do it right. A walk in the park for you. I reckon you know already.I'll keep a lid on it now.
Return to wallpaper thumbnails.