The first part: All the people who came for baptism asked John, "What must we do?" To the rich he says share your food and resources. "Share with the man who has none, and the one with something must do the same." The soldiers and tax collectors are told :No intimidation! No extortion! Be content with your pay."
The second part: John addresses the feeling of expectancy among the people that he might be the Messiah. John is very clear. He baptises with water, but the one who is to come will baptise with the Holy Spirit and with fire. "He is more powerful than I am. I am not fit to undo his sandals."
Among the many other things that John said to exhort the people and to announce the Good News was this phrase: "His winnowing-fan is in his hand to clear his threshing-floor and to gather wheat into his barn: but the chaff he will burn in a fire that will never go out." This reflects the hell-fire stern teaching of John. Repent means to change your attitude or be swept up and burnt. The gospel of try-harder or burn was all he knew. But he did know and was waiting for the more that was to come with the Holy Spirit and fire of the Lamb of God.
We note that to this day there is a small number of John's disciples that have not changed to be followers of Jesus. We know that Andrew and Peter were probably disciples of john before they met Jesus. At the time of Luke's writing this was probably a big issue and is being addressed here.