When? Did you tried to run this example script?
<?php
include('whois.main.php');
$whois = new Whois();
$query = 'daniweb.com';
$result = $whois->Lookup($query,false);
echo "<pre>";
print_r($result);
echo "</pre>";
?>
It works if the script example is in the same directory of the PHPWhois Class.