EASIEST method is to use a router, and ethernet cable (cat5 or cat6, with rj-45 ends). They're called patch cables, and are sometimes much cheaper to make than to buy if you get the tools. Don't pay more than 50 cents to a dollar/foot for the patch cables, or you're being ripped off. The router is a switch with a bridge, and special networking firmware. The switch is a type of hub, which allows local traffic to transmit between the computers. Each computer gets a cable going from the router's LAN (local area network) ports to the computer's LAN port. The router does all the hard work these days, automatically assigning IP addresses to each node on the network. the Bridge connects the router network, through NAT (network address translation) to the internet, if you have one, through the WAN port (Wide Area Network). The internet is an expansive WAN. If each computer is configured in the same workgroup (right click my computer>computer name>and you can change the workgroup - make them all the same, but with a different computer name -- then the computers can 'talk' to each other for gaming, file transfer, or other generic data usage.