Danny,
I'm afraid you need a router to share your NTL connection - not a switch. In the page you linked, the switch plugs into a router which in turn plugs into the Cable modem. The switch you have is designed to expand an existing router - ie from a router with 4 ports to a router with 3 ports plus switch with 4 more ports. The Netgear router is
here.
I hope you are able to return the switch