Unfortunately http://www.web-cyradm.org/ is down now
The cyradm.php included in web-cyradm is rather fragile and doesn't work with recent php releases anymore
If you have problems using this package you might want to take a look at web-cyradmin (http://www.web-cyradm.org/). It has a PHP class called cyradm located in the lib/ folder that has methods for most or all functions you might need to perform in cyrus. (Version of web-cyradmin is 0.5.4 as of writing). Example:
<?php
require_once("cyradm.php");
$GLOBAL['CYRUS']['HOST'] = "localhost"; // or wherever you keep your cyrus server
$GLOBAL['CYRUS']['PORT'] = 143; // or the port you use for IMAP traffic
$GLOBAL['CYRUS']['ADMIN'] = "cyrus"; // the cyrus admin
$GLOBAL['CYRUS']['PASS'] = "secret"; // password for admin
$cyradm = new cyradm();
$cyradm->imap_login();
$cyradm->createmb("user.username@domain.tld");
$cyradm->imap_logout();
?>