Windows comes with a default unzipper afaik. Else you can easily get other free 3rd party unzippers.

Check http://www.gnutellaforums.com/host-c...bearshare.html & be sure you remove the files from the unzipped folder & drag & drop them into the folder you need to & click yes to replace the older files inside.
That link shows an example for the BS Beta 5.1 & although you do not necessarily need to use that version, it would most likely be better than 5.2 Lite version in many ways. BS 5.1 Beta is more or less equivalent to the BS Pro version. The BS 5.1 Beta lacks UPnP support however which means you may need to port forward your router 'if' you are using a router.