You have to configure the access point and the AirPort card to use the same wireless network name (sometimes called SSID) as a begining. It isn't a "right out of the box" set up, but it isn't too difficult, either. Break out the book on the DLink box and look up the manual for your AirPort card, and follow the instructions.
Not hard, not even too complex, just a few steps to take to tell both devices about the other.