How does the bus between the two towns work, and where do I pay?

I stay near the Cabo San Lucas marina for part of the year and I would like to spend a day in the other town. It is about thirty minutes by car and I have heard there is a bus. I do not know which stop to use, which side of the road to wait on, or whether there is a timetable. Do you pay on board in pesos, or buy a ticket somewhere first?