A market is only for a specific good (hides/corn/wood/etc.) on a specific tile (Monterey/Los Angeles/etc.).
So in the beginner rules, when you play a market, somebody collects $3 and that's it. In fuller versions of the rules, other players will be able to participate in the market via roads.
Ok, thank you for the fast reply. I guess I should not put too much attention to the Beginners' Game, they seem to be more or less there to explain just what you have clarified above. Onward!