Configuring a LAN used to be a real pain. You had to manually assign a network address to each device on the network, and keep a record of them to make sure that you didn't use the same one twiceif you did, both devices would stop working. However, modern LANs with routers using a system called DHCP.

DHCP stands for dynamic host configuration protocol. It's a fancy way of saying that when a device connects to the network, it asks the router which addresses are free, and then the router allocates one to it for a limited amount of time. This allows you to connect and disconnect things from your network whenever you want, without having to configure them. Even if your laptop has never connected to a network before, you can just plug it in, and off you go, without needing to know anything about how the network is configured.

In general, to get a modern network up and running, all you need to do is wire up each computer to the router using an Ethernet cable. Often this will be enough to get the computers to see each other, but occasionally you need some extra configuration. In Windows, the easiest way to configure a network is to go to My Network Places on the desktop or the Start menu, and then click 'Set up a home or small office network'.

Once you've done that, any printers or other devices that are connected to any of the computers, or to the router itself, will be automatically shared. If you want to share individual folders between computers, that's also simple to dojust right click them in My Computer, choose Properties then the Sharing tab, and then put a tick in the 'Share this folder on the network' box.