Many people have relatively uncomplicated needs for their home networks. Even now that multiple computers within a single home are common, the systems are often not networked, with file transferred being done by means of "sneaker net", or copying files to and from a CD or by sending files via email.
This is a great time to build your own home network, if you have always wanted to. The costs and the complexity of the systems are lower than ever. Just getting past the technical terminology used is the largest barrier for many new home network builders. The equipment you'll need is pretty simple. You're going to need Cat-5 (or Ethernet) cables for a wired network. Think about where you plan to set up your computers to determine how much cable you're going to need and then add on about 1/5 more cable than that – you always need a little more than you think. If you plan to build a wireless network, you can skip the cables.
You'll also need a switch or a router for all of these cables (or radio waves if it's a wireless network) to connect to. A hub or a switch is just a box with ports to plug cables into – a switch has slightly more functionality than does a hub. A router is better and can handle internet connection sharing; it is almost a must for a home network. I say almost because you can use one of the computers on your network to handle internet connection sharing. However, it is in most cases far easier to just use a router instead of tying up a lot of the resources of one of your computers dealing with connection sharing.
You're also going to need Network Interface Cards (or NICs) in each computer, printer or any other device you want to be on the network. These can be your standard 10/100 ethernet cards or 802.11b / g cards which can be used for a wireless network. If you are building a wired network, you can use Ethernet equipment with 10MB or 100MB speeds. They are both so inexpensive, that there is really no reason not to go for the 100MB equipment. These devices generally support equipment which runs in the older standard as well. There is also Gigabit Ethernet, but this is prohibitively expensive for many building a home network.
Install, attach and / or setup all hardware as per the manufacturers' directions. Every device on the network needs to have at least one IP address of its own. IP addresses are those numbers you may have seen on the internet before, such as: 70-1-2-125. On a home network, your IP addresses will look like 192.168.0.1 or 10.121.0.1.
Your IP numbering should begin with the router. This device is the center of your network; Imagine a star with rays of light emanating from it. Each cable or wireless signal is one of these rays of light. The ends of these rays are where your devices are. If the router has the number 192.168.0.1, then computers and other device should be numbered 192.168.0.2, 192.168.0.3. Do not assign the same address to two devices.
You'll have to read the manual for your router for the specifics on how to assign these addresses, as well as the documentation for your computer's operating system.