Now plug the modem, as we have already done, into the hub or switch and connect the computers to the same device. Your internet connection should work now from any of the computers.
Example: You turn computer 1 on and start the internet connection. PC 2 and 3 will use computer 1 as their gateway if there is already a live connection on the network. If you turn PC 2 on first and start the internet, then numbers 1 and 3 will use 2 as their gateway to the internet.
The schema below will show you what I am talking about.
Have fun on the internet!