Start
here.
You'll need a wireless router. Preferably an 802.11g standard router. (It's faster than 802.11b). Then you'll need a Wireless NIC (Network Card) for the laptop. Unless, of course you have a laptop with an integrated wireless card.
Then, it's just a matter of setting up your network, which is done through the router. Don't forget to set up some security, which again, will mostly be done through the router software.
It's all pretty simple if you follow the directions that come with the router.
Randy