Ok. The bridge mode is not guaranteed to work other than with two dap-1360 units. Thats what is says in the manual. Because you have a dlink dir-815 router, I assume you are using it as a router / WLAN to access the internet with computers / laptops etc. And you now need to get the DENOn to get internet too.
I would recommend you to use the DAP-1360 as a "wireless client" instead, easy to setup and will work the same way as a bridge, bridge mode is only useful if you need to share local recourses like files etc between windows computers etc. If that is not the case, and you only need internet, "wireless client" is what you should use.
http://www.support.dlink.com/emulators/dap1360/101/wireless.htm
Hook up the unit to a computer with lan cable, configure computer so you can access the unit, surf to the unit with the browser. Do not use wizard as it is not needed. Go to wireless setup page and configure it for the settings you have. The manual has great info on configuration, with wizard or not.
In short, what you need is, "wireless client", "infrastructure", use site servey, then you need to enter password for the dir-815 unit. Make sure the DAP-1360 is useing DHCP and change "device name" to something like dlinkap4
Shut down the unit, reconfigure computer to use DHCP (standard network settings), start up the unit. Now you should be able to surf to http://dlinkap4 so you can login to the unit and it should be connected and you should be able to surf on the Internet with the computer. If that works, now you can just shut down the dap-1360, hook up the dennon, and thats it.
------------------------------
Now that the unit is connected over WLAN to the dir-815 you should be able to use any computer on the LAN to access the DAP-1360 on http://dlinkap4 in any browser, if you need to change some options and so on.