how to add new atrribute using php

["Juelia" <kurank@lycos.com>]

Hi.

I'm very new to ldap, so please someone help me with this.Currently i have (in my ldap)   
    cn
    title
    uid
    mail 
    telephonenumber 
    objectclass

Let say i want to add localityName here? How to add this new attribute in there using php?

Thanks for any help.