Basically, one user has to be host. Let's say that is John. John is hosting the server so he most likely will be captain (doesn't have to be the situation of course, just works nicely since he'll have main).
Pre-game:
John needs to configure his internet/wireless routers for the game. John portforwards port 2010 to his computer. (If you need detailed info on this, email me and I'll hook you up.) John determines his WAN IP by going to
whatismyip.org (e.g. 69.61.171.116), John remembers it.
John gets all of his crew members connected to a voice chat service, TeamSpeak, Mumble, Skype, Google Hangouts, etc.
John starts up Artemis and chooses "Start Server". Windows may ask john to allow access, John accepts.
John's crew members now get to take action. John's crew starts Artemis in Client mode. John's crew enters John's WAN IP address and selects Connect to Server. John should see connection chains populate under the server settings.
Once John's crew has taken their positions John starts the server and they all merrily kick some Kralien ass.
Note:
John can connect a client to his own computer, he just needs to use 'localhost' or '127.0.0.1' where he would normally put the server IP.
If that wasn't detailed enough, email me and I can answer any and all questions you have.
I'm also willing to train on different stations on the weekends if your crew needs it.