Ah - good choice - this is one of my favourites! I suppose you what to know how to get it on the desktop now. Getting the wallpaper onto your desktop background can be done in a number of ways. 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! Then set the desktop background using your computers OS's desktop or display control panel and select the image you just saved.
Another way is when the full screen wallpaper is shown, right click it and select 'save image as...' or 'set as Desktop Background' or 'Set as Background'. You'll know what to do when the time comes. A walk in the park for you. I bet you already know. I'll shut it now then.