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 desktop wallpaper beow and then select 'save target as...' (IE & Opera) or 'save link as...' (Firefox). If this is your chosen route, remember where you save it! Next goto your computers display control panel and set the background to the image you just saved.
Instead you could, when the full screen version has loaded up, right click it and select 'save image as...' or 'set as Desktop Background' or 'Set as Background'.When you're ready - you'll know what to do. I think you have it in you. You know already I'm sure. I'll keep a lid on it now.
Return to wallpaper thumbnails.