first you need to download the app (http://www.hoverdesk.net), then after installation, if you want to change a theme (i think it's your question here), you have to drop the downloaded theme file (zip file) onto the HoverFesk main tile.
To locate the main HoverDesk tile, simply hit the keys : WinKey+H and it will start blinking.
Yep, listen to him, he wrote the damn thing. What you see up here at Customize are just the themes for Hoverdesk, you need the actual program to use them.
