DSL-N Ignorant novice needs help configuring wi-fi

I recently installed DSL-N on an old lappy. I have a wi-fi card, a
DWL-G650, and it seems to be working okay (LEDs flashing etc...).

As for configuring wi-fi access, I'm stuck. Linux is not my familiar
stomping ground; I'm more at home with the rounded icons of OSX.

The wireless connection is provided by an airport express base-station.
Here's what I know about it:

I know the name of the network. I know its IP address. I know it has WPA
Personal security and is protected by a password.

There are three programs in DSL-N that look relevant to my needs. They
are: netcardconfig, iwconfig, wlcardconfig. But as far as using them,
I'm completely at a loss.

Could someone hold my hand and give me a step-by-step guide to
configuring this thing? I could really do with the help.

--

I need more time!
.