This plugin installs a google search bar entry for "Man pages". This will connect to the web server (such as Apache) installed on your PC and display the results of a man page search.
This plugin was written for Firefox 1.5. It probably doesn't work in Firefox 2, and definitely doesn't work in Firefox 3. There are better ways to do it now. This page is maintained as part of an archive of the old website.
To check if you meet the above requirements, try to load this URL: http://localhost/cgi-bin/man/man2html. If it succeeds, you can install this plugin.