How do you connect computers to each other in a network?

at our house we have two desktops, a laptop and a printer, all in the same room, and we'd like to be able to access all of them from each other, as in, print from any computer, and access any of the hard drives regardless of what computer we're on. We have a clearwire modem and a belkin wireless router. The router is connected to all the computers, so they can all access the internet just fine, but how do you get them networked after that point? And how do you get the printer connected to the router and all the computers?