Wiring up a LAN (local area network) can be very easy, or it can be very difficult – it all depends on the size of your network, and how you’re trying to go about it.
For a very small home network, you can get by without using any special equipment except the wires. If you want to use a network to share Internet access or a printer, just plug an Ethernet cable into the computers you want to network, and then use the simple networking features that are built into Windows, such as Internet Connection Sharing. This approach has many downsides, though – you’ll need an extra Ethernet card in each computer for every extra computer you connect to the network, for one.
Instead of connecting each computer to the next, it is better to simply connect all the computers to a central router. This is a very efficient way of connecting computers together, as the data you send will be quickly and easily routed to its destination: the data goes to the router, which knows which wire to send it down for it to reach the destination address, and simply sends it that way. This also allows you to turn on and off computers as you please with no ill effects, as the router is always-on.
If you want to connect more devices to the network than the four or five ports on a router will allow, then you need to get a network switch. This allows you to create a separate sector of your network especially for one group of devices. For example, you might have your computer and your printer both plugged into a switch. The computer and the printer can then communicate between themselves without the data needing to travel out onto the wider network – but if they want to send to or receive from the wider network, they can do that too.