Netgear ethernet connection

Make sure your cable is fully inserted into both the modem the router. also, ensure that you connect your modem to the router, make sure it's in the "internet" or WAN port (same thing, different names) and not into one of the PC slots (normally numbered 1,2,3, etc) and vice versa for connecting your PC to the router.

This is all assuming of course that you're connecting to a router / switch of some sort. if not (if you're trying to connect 1 PC to another) then you need what's called a crossover cable.

also, when you plug in, do you see a "link light" (usually indicated by a green LED either on the front of your router or on your NIC if a good connection is established (most likely you won't be getting this if you're not communicating, but if you are then knowing that definately helps to narrow down the possible problems). If you don't have a link and you have an extra cable handy, try using that one (mechanical failure is a fairly common problem, even in brand new components)

If you're still not fixxed and have any more information about what you are trying to do / what you have done, please do post that information.