Ok I'll do my best here. Your going to have to unhook the DI524 from everything else to get into it. First just disconnect the DI-524 and connect it to only a computer. Open web browser of said computer and type the ip of the router, I'm pretty sure d-link uses 192.168.0.1, in the address bar. This should bring you into the config page. I'm not sure if that's all you needed and hopefully that works. If you need help setting up the rest read on.
Now you're going to want to turn off DHCP in the settings. Setup all your wireless info. Network name, password etc. Save and exit.
Now you want to run a cable from the DIR-825 to a LAN port on the DI-524. Do not plug it into the WAN port.
Connect everything else as you see fit.
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Here force failed my high fantasy; but my
desire and will were moved already-like
a wheel revolving uniformly-by
the love that moves the sun and the other stars.