By a router (any will do so long as it has enough ports for now and perhaps an extra or 2 if you upgrade later). You simply release your IP from which ever computer the modem is in. Then you plug the modem into the router and it should get an IP and dish out local IP's to all other computers. Then all you need to do is set up file/print sharing if you want it.
18.98Ghz of Cancer killing power commin at yah.