You can have more than 1 barracks! I suggest at least 10 barracks per town. As a new player you can usually run 10 barracks and 10 cottages. More advanced players can sometimes run towns with 14-16 barracks!
I see a lot of new players with only a few barracks. It is impossible for them to keep up with me if they can only make troops 1/4 as fast as I do.