Hello Janathan.
Adding D-link to your network does not require any additional configuration of your Cisco devices.
D-link wireless router performs NAT service for users conneted to its LAN (cable or Wifi).
So in your cisco network, these users would be represented by one address - the address of the D-link WAN interface (connects D-link to Cisco router).
Let's say, for example, you have subnet of 192.168.5.0/24 between your Cisco device and D-link wifi router. You have to configure static IP address of the WAN interface of D-link, let's say 192.168.5.1 .... all users behind D-link (on wifi or eth lan) are represented by address 192.168.5.1 in your cisco network (because of the D-link NAT).
So you do not have to configure anything new on your Cisco devices. 192.168.5.0/24 is already known on your network.
Hope this helps.
Martin