If you have a "playlist" in iTunes called something like "Nitsuj2009's Limewire tunes" This is not a true iTunes playlist, and it cannot be edited. It is a list of your shared tunes. You need to add your tunes to the limewire Library and this link should help.
http://www.gnutellaforums.com/showth...threadid=36230
You should then be able to edit anything on the tag by clicking "get info" As LOTR says Windows may be alittle different, and I also use mac, but I think this will help.