When you run a normal network you need wires going from your pc to another hub/pc.
Wireless uses a wireless ariel. The hub and each pc will have to have a wireless connection. You can get wireless PCI cards for your pc, but a hub will have to be a wireless hub, you can't convert a normal hub into a wirless one.
The whole point is that i cuts the hassle out of messy networking. Say you got 3 or 4 computers and you want to network them. 1 maybe a downstairs, 2 in the bedroom etc... You can imagine all the wires trailing around the house can't you? Well with a wireless network you don't have the wires. No more metres and metres of wire going around the house!