What is inside the .zip-file? If a .bsz-file: unpack it.
If more files: change the .zip extension into .bsz .
http://forum.bsplayer.com/bs-player-skins-skinning/10601-how-add-new-skins-bsplayer.html#post39978
Did you copy/move the .bsz-file into BS.Player's Skins-(sub)folder (which is inside BS.Player's installation folder)?
Do you see the skin if you select (rightclick >) Options > Skins (or use [Alt]+[S]-keycombination)?