It was an easy process for me. Go to
www.whatismyip.org Then type http://'ip address' into the address bar, with the ip address being what you got from the "whatismyip" site. This is how I get to my router control settings. You may have to enter a password which whoever set up the router created, assuming you're not at work or something, it shouldn't be an issue. It's different for each router, but on mine, I click the "Application & Gaming" tab. Under that you go to "port range forwarding." That's what you're looking for. Then in one of the boxes for Application, type DC++ for whatever, and pick a port to use for DC++. You could just use 5666, as that's one that's not used for something else. It starts and ends at that, and you enter the IP extension for your computer. I'm not sure about the dynamic IP address thing, since I don't have that issue, but it seems to me that this is not it, the active IP address I enter in the DC++ box is different than the one here, the one here is like the router ip address, with an extension identifying which node on the router you are, so like xxx.xxx.x.1 or 2 or whatever. What you got from what is my ip with the extension.
Then you go to "connection settings" in the DC++ settings menu, and for TCP and UDP ports type 5666, or whatever port number you chose to forward. If you have your IP address entered there, it should work.