To use Services_Mailman, you need to include it into your PHP file:
<?php
require_once 'Services/Mailman.php';
?>
Then, create a Services_Mailman object and supply the "Admin Links" URL and the admin password:
<?php
$mm = new Services_Mailman('http://example.org/mailman/admin', '', 'adminpass');
?>
If you already know the mailing list you want to work on, specify it as second constructor parameter:
<?php
$mm = new Services_Mailman(
    'http://example.org/mailman/admin',
    'foo-users',
    'adminpass'
);
?>
   If something goes wrong, Services_Mailman's methods will throw exceptions
   of type 
   Services_Mailman_Exception.
   Using it's getMessage() method will give you
   a human-readable error message.