The port can be anyhting above 1024 that is same for both the host and all the people joining. So, in addition to your ip-address, tell all the players the number of the port.
Originally posted by garvoid2: ALso can the computer play in a MP game?
Wait, are you asking if the server can also play as a client? Just open another copy of Dominions. I regularly host Dominions servers, you can always ask me for help.