It's not common sense at all - it's knowing how to do something. Which is not the same thing. Additionally we have half a story here.
Plug each of the PCs into the Home Hub (I assume that's what you mean.) with Ethernet cables. That's thr hardware done. Now, assuming Windows XP, click Start, Connect to, Show all Connections. On the left of the pop up window you will see a phrase: "Set up a Home or Small Office Network". Click on that and follow the instructions.
Terry
January 2007