Wifi

You need to purchase a wireless router. The router will have 5 ports on the back, one in and 4 out. The wire that you have going from your modem to your computer will go to the "in" port on the router. The out ports can be used for wired connections, and the wireless antenna will connect to any wireless computers.

Any computer that you want to connect wirelessly to your new router will need to be wireless-ready. For a desktop computer, you will need to buy and install a wireless PCI network card. Most laptops have built-in wireless.

You can buy a wireless router at most "big box" stores, like Best Buy, Office Depot, even WalMart sometimes carries them. A wireless router will cost between $75 and $150.