Sounds like you're using the "Multiplayer" button from the game's main menu, rather than the "Ironclad Online" button. The Multi button is for local network play, so in order to play with others online, you'll need to use the ICO button. Once you've created an account, logged in, and added a player name to your account, you'll be able to join the chat lobby and look for games.

The best way to actually FIND an enjoyable game with people who know what they're doing is to come to the IRC channel #sins on irc.stardock.com and ask if anyone's up for a game. I find that on ICO I always run into folks who are either playing their first game of Sins or really didn't quite understand how an RTS works yet. The thing is that this kind of game is really boring to the more competitive player, so the players who've moved beyond this stage stop playing games on ICO.