connecting Cisco DPQ3925 wi-fi modem with airport express

I currently run internet with an old Motoirola Sideboard cable modem and Airport Express - previous version. All runs well. Now my Optus provider has upgraded my service with a Premium account for higher speed. They have also given me a free wi fi Cisco modem - DPQ3925. How can I replace my old Motorola modem and still maintain Air play etc with my new modem using Airport Express. I need to know exactly wire per wire help - please, if possible - Thanks