You can read more about cookies at the cgi.pm site.

The full parameter list (from the cgi.pm site:)

$cookie = $query->cookie(-name=>'sessionID',
             -value=>'xyzzy',
             -expires=>'+1h',
             -path=>'/cgi-bin/database',
             -domain=>'.capricorn.org',
             -secure=>1);
    print $query->header(-cookie=>$cookie);
[download]

To retrieve the cookie in a cgi script and put the value in $cookie_data: $cookie_data=$query->cookie(-name=>'whatever');

/wonko