how do I configure the Asus wlan card to connect to fritz box 7272

You should have a manual for it, often it's on a disk that came with the router. It will tell you how to get to the setup page to configure the wireless settings on it, then you can setup the wireless on the computer to connect using whatever security setting and password you setup. I suggest you use WAP2-PSK security. If you don't have the disk you can get the manual here http://fritzbox.com.au/user_manual.html