Connect both to a router, enable file sharing on both (if desired), and you're done. It really is that simple. The router handles interconnections and providing Internet connectivity for all its LAN ports, so all you have to do is tell the computer it's connected to a LAN and you're set.
(Note that "telling the computer" varies quite a bit with PCs, depending on which OS they're running. It's not hard, but it's different from one OS to another.)