If you have a broadband Internet connection with one computer connected to it, you may eventually need to share that connection with other devices.
For example, in my house we have the following:
Vonage Internet Phone
When your Internet service provider gives you a network connection, it only has a place to plug one thing in, usually a PC. So this is what you need to do:
Buy a router with a built in switch. If you want wireless Internet for a Laptop or Wii or other wireless device, make sure it has wireless capability also. Make sure there are enough ports for everything that you have, and anything you think you may want to buy in the next 1 - 2 years.
A router has one port that is labeled either Port 0 or Internet. This port connects to the Internet modem that your Service Provider installed. The other ports are usually labeled 1 - 4 or 1 - 8 depending on the number of ports.
You should already have a cable for each device, but if you don't just buy an Cat-5 (Category 5) or higher cable for each device that needs an Internet connection. The exception here is if you want to use wireless (Laptop, Wii, or other device that has a Wireless card.)
The next step is to plug the Cat-5 cable into the network card on the device and then into one of the ports on the router. The default configuration of the router should have you up and running, unless you have a DSL modem that requires you to log into the network. If that is the case, you need to follow the directions that came with the router to configure that, since every router will be different.
If I missed anything here, please send me an email or comment so that I can correct it, or if you need further help.