[CentOS] CentOS 5.2 -- how do I choose a wireless network?

Hi. We have a Windows laptop that has gotten too slow, it's borderline unusable, so I burned a CentOS 5.2 32-bit Live CD, just to try it out in the home.

It boots up fine, but it does not connect to the Internet... Now we normally connect through a wireless network, there are several around here -- on the Windows box we choose the network to which to connect... but on CentOS there is no such menu?

I went to Administration -> Network, and enabled the wireless interface, set to Auto and to DHCP, but it said, unable to assign IP address, and no connectivity...

How do I connect to a wireless network, please?

Thanks, Aleksey