How to import a skin?

Hey guys. I 've recently found out some pretty cool skins, just like this one:
http://www.artodia.com/demo/index.php?style=16y
I really liked it, so I downloaded it, in ZIP format. Then I went to Display/Themes Management and I found the option import the skin, and I thought this what I was looking for. The thing is that I don't know which format should I import it, or which file. I mean, should it be uploaded in zip directly (tried, but no difference was made to my current layout) or should I unpack it on my PC and upload a specific file. This is my forum:
http://zetamakripoulia.forumotion.net/forum


Any help would be great.

Sorry but that skins can not be inserted in forumotion. These skins are only available for phpbb3 original forums.

Only hitskin's themes working for forumotion. The only extension: .bbtheme

Thanks a lot for that