How to make a Internal IP available for people outside our network?

Hi there Guys, 

Im new in the Windows world, which means im new to Sophos Firewall aswell. We have a windows 2012 server and that server can be accessed with a hostname outside our network. I want to add another ip on our firewall that can be access outside our network.

What i have done so far:

1) On our server given the IP a hostname= 192.168.1.2 is now internally accessible through accfin.fvln.co.za:8080

2) On our XG125  opened ports 80,443,8080.

3) Set Source Zone to be WAN

4) Destination to be our Port 2 (which is our broadband internet port)

5) Forwarded to the IP above which is 192.168.1.2

What I need to accomplish is we have a java server running where clients outside our network needs to access this server via die hostname we assigned to the server

But i still cant access this outside our network, what else needs to be done? 

With linux its easy using a Bind Server and adding a zone at your ISP, but im really having a hard time with this one.