You must install Rainmeter 1.3 to use this skin:
http://rainmeter.net/RainCMS/

It's advised that you read the readme if you're new to omnimo. 

Also it's highly recommended to hide the desktop icons before installing, if you wish to use desktop icons with omnimo, close the background by right clicking it and selecting close, and then rearange the layout. You can also use Stardock Fences as mentioned in the readme.