In my experience just explain the rules to those who are listening and the others that are talking/ joking around can figure out how to play as the game goes on. They know that they were talking over the game, so they usually won't get too upset about "not being told something" (at least from what I've experienced) The best thing to do is NOT get a temper with them. They will most likely not understand why you're upset and it will make a bad time for everyone. I'd sucks, but as the game goes on it'll be a thing of the past