The average age here is about double that on battle.net so that helps a little
I recommend playing in single player, getting a good handle on your nation of choice, and then joining a newbies game. They start from time to time. In a mixed game, you'll likely get clobbered unless you have lots of experience in multiplayer turn-based strategy, and dom2 takes so much time to play that its really better to play with people of similar skill. But even the veterans are generally pretty helpful and friendly.
Of course, ir r00lz pwn u. Or something.