Ahh, you need a wireless game adapter for your PS2 that will receive the signal. .
Amazon.com: wireless game adapter
It plugs into the Ethernet port on the back of your PS2. You can get a decent one for $40
First find out if you have a Wireless B or Wireless G signal first. I think some adapters can use both. That list above is pretty decent though. I wouldnt go to the linksys product site because they only list their newest (and most expensive) ones.