update username using datamanager

[khan3332]

i have the username update code below

$userdm =& datamanager_init('User', $vbulletin);

$userdm->set_existing(fetch_userinfo( $vbulletin->userinfo['userid']));

$userdm->set('username', unhtmlspecialchars(trim($vbulletin->GPC['uname'])));

$userdm->save();

can someone show me how to print out a message saying

your username has been successfully changed and redirects

to the main forum page after this code, thanks