D-Link, like most access point makers lately, makes it very easy to set up the device using your Internet browser.
Taz is correct though in noting that you may have to fiddle around a little with your WEP key. It usually works easiest to generate a hex key either externally or with your non-Apple wireless device, then enter that key in your AirPort device. Depending on the version of the Admin Utility you have, you may not have the obvious selection of hexadecimal key entry, which is the standard for every manufacturer other than Apple. If you don't see a button or check box for hex entry, simply start the entry with "$" (without the quote marks, of course).