How are you doing buddy,
Your problem is that you don't know the correct IP address for your router.
Rather than guess at it, you can check it by clicking the Apple Menu - > Settings - > Network - > Select Network Interface (Airport etc) -> Advanced
and then on one of the tabs you should see an entry for "Default Gateway" or "Router" and this is your Routers web interface address.
Hope this helps, it's from memory so might not be 100% correct!
Best,
John
Sorry didn't fully read the question!
If you are connected directly to the Airport express wirelessly, the IP address of your DLink router won't be avaiable in the method i've described.
Easiest option is to connect directly to the DLink device via ethernet and do what I suggested above, failing that it would depend if the DLink router is in bridged mode or routing mode as to wether you can login to it over the express,
Message was edited by: JohnAlanWoods