Freeview HD tv - which wire do I use?

[jb7]

I have a wire coming from the rooptop aerial which plugs into a two way socket (beause there's two tv's that use the aerial). Currently only 1 tv is connecting so there's one space empty on the socket - I have been told I need a 'coax' wire to connect that socket to my new freeview HD tv. (i.e a wire plugs from that socket into the aerial port on the back of my tv)

but which wire is it that I use? There appears to be lots of different coax wires with different 'ohms', could somebody please provide a link or information about the appropriate one? Preferbly with the plugs already on the wire

thanks