Shoutbox

Erm simple!  NTL doesn't use usernames and passwords.  Use a network cable to connect the modem into a router (Must be straight through i.e. all the wires in the same order at both ends)

Set the external port (the one connected to the modem)  to accept a DHCP address (basically it aquires the external  IP address from the ISP)  now configure the internal router i.e. the other ports connected to local machines.  (You can do this manually or some routers have a DHCP server feature)  All the machines need to have a gateway set (This should be the routers internal IP address)

Hope this helps