If you want to make your server public, forward ports 6000-9000 tcp-ucp (this is not secure, but I cant remember the ports you have to forward), and change the ips in System.xml, Locator.ini, Server.ini, AgentServer.xml (something like that O.o), the Serverstatus database and Locatorstatus database to your external ip (also called WAN IP)
Theres always a solution of buying a dedicated server, where you can host the gunz on, that way, no lag, no portforwarding, and professional hosting xD