It works a lot like your cordless phone at home. From there, the data travels by radio waves, to and from the computers using the access point.
Many laptops have the antenna built into the lid, and the card installed internally.
This presents many attractive possibilities for schools. For the first time, it will be possible to bring a lab to a classroom, instead of the other way around. The teacher or media person will roll a cart to the classroom, and plug in power and network to the cart. Students will take a laptop from the cart and work at their desks. The laptops run on the internal batteries, and access the network and internet over the wireless link.