If from your pervious thread you should have the following :
Local IP : on the Cobalt
WAN IP ( public IP ) : on the router
Considering that you have a static IP address from your ISP, you will need to point your DNS "A Records" to the WAN IP of your router.
The router will then do the rest of the things like forwarding various services to your server.
You will need a domain host that allows you to setup your DNS records and not just allow you to specify the nameservers. ( This is VERY important, I had countless subscribers that did not understood this and need to get another IP address to run their own DNS )
If you are running the RaQ4 OS, then the initial site's IP address needs to be modified on the network settings I think.