Hello,
I have manage to build a small game that you can run over a network and enter your ip address, however, how would i run this game on my local network and connect to it externally using an internet ip address for the server??
Or, how would I run a game that creates a server that can be connected to via the internet?
This is a feature available to you in Unity ( for small games, anything over 32 players is not recommended ):
http://unity3d.com/support/resources/example-projects/networking-example
Take a look at this, and you should be able to derive what you need to do exactly what you want. Take a good look at NAT Punchthrough as well, which is a feature that is built into the Unity Networking stack. NAT Punchthrough resolves issues with router and firewall dependencies so you can connect via WAN and not just LAN.