In my copy of the book, this happens on pages 18 and 19.
The first thing that happens to Kumalo is that a young man cheats him out of some money -- one pound. He helps Kumalo to find the bus station, but then he tells Kumalo to give him the money and he will go buy Kumalo's ticket for him. As it turns out, you do not pay for your fare until you are on the bus.
Kumalo finds this out, and gets help to find where he is going from an elderly man whose name we later find out is Mr. Mafolo.
I must admit that there isn't much to add to the first answer in that this is one of the first things that happens to Stephen Kumalo in the book (and we are not very far along in the plot when this happens). Stephen Kumalo gets duped out of the money for bus fare, learns how to pay for the bus, and gets directions from an aged gentleman.
Stephen Kumalo is trying to figure out how to get to Sophiatown by bus, so he asks someone near to his own age to help him. Unfortunately, the boy tells Kumalo that he will buy the ticket for Kumalo. After Kumalo gives over the money, the boy (and the money) are gone! The only thing the boy actually helped with was finding the bus station.
This is where Stephen Kumalo's first mentor, Mr. Mafolo, comes in. He gives Kumalo some important information: one can only pay bus fare when entering the bus. He also helps Kumalo figure out which bus goes to Sophiatown. In my opinion, it is the first time that Kumalo discovers this ultimate truth that he reveals later in the novel:
But there is only one thing that has power completely, and this is love. Because when a man loves, he seeks no power, and therefore he has power.