The final part of the dynamic dns setup is to forward on the dynamic dns to our raspberry pi so that we can serve content on port 80 and port 443.
I will try to make this relatively generic so that you can use it with your router.
This is the part where my ISP may be concerned about me serving content from my home internet connection. As I keep saying, this is a test to see what is possible with a low powered device like the raspberry pi.
Login to your routers admin panel via your favourite browser. This generally lives at 192.168.1.1
There should be a setting under advanced that will allow you to set port forwarding. In my case it is under the NAT section.
Set your protocol to be TCP and set the LAN address to your raspberry pis address on your local network. Mine is 192.168.1.234.
Set the private port to be 80 and the public port to be 80 and then do the same again for port 443.
You will also want to fix that IP address for your pi on your local network. This should be under the DHCP section of your routers settings.
Save your settings and now your pi should be serving content to the outside world via your dynamic dns.