Easy: translate main page in Polish at frostwire.com/index.php?title=Main_Page_PL
Then we'll add a link to the language menu.
You can also translate any page by adding the _PL suffix of any web page you want to translate. If you have questions, pose them here, I translated the wiki to french.
Make sure you also register the wiki to help further develop the web site and vote on polls.
Your Polish translation would be very welcomed, BTW I_added your site to the ones we will contact once FW is released
Ciao