How do I ride the houston metro?

Recently ive found myself in a not so great situation, and I need to start taking the bus. Only problem is, I dont know how at all. Say I want to get to stop 30 and the closest stop to me is stop 20, and I need to get to stop 30 at X time. What exactly does that process look like? Do I just show up at stop 20 at the scheduled time and eventually the bus will get to stop 30? If so, how do I know at which specific time the bus will get to stop 30?