You put money in the fare slot. Bring change. After the first time, you'll know the cost and you'll have to remember always having that amount with you, coming and going. You tell the driver where you're going. After you learn the scheduled stops, you'll know when to stand up and start moving toward the front of the bus.
I rode bus for a long time. You pay for your ticket, you may need exact change. Then ask for a reciept. You may need a transfer sometime, be sure to not be shy and ask driver for any information you need. Also, pick up a schedule in the bus. It is useful.