cable modem motorola

Sorry to be in english. Hello to all.I have the ip casema and the cable modem motorola sbv5120e,i like to connect a satellite receiver to the net.I try to acess the setup from the modem to make the port forwarding to the receiver buth is not posseble,can i connect a router sitecom and make the port forward on the router???? Thanks to all. PS: The Portuguese......