John the Baptist Prepares the Way
John the Baptist is a preacher who seems to be preaching about end times "Repent, for the kingdom of heaven is at hand". People come from all around to get baptized by him. When the Pharisees and Sadducees come to get baptized he calls them a "brood of vipers". He baptizes them and says they need to repent and "bear fruit" or he who comes after me will "baptize you with the holy spirit and fire".
So if I am reading this right, basically john the baptist goes ahead and baptizes anyone who comes along, but warns them if they don't shape up they are going to hell. He's the original fire and brimstone preacher then?
The Baptism of Jesus
Jesus goes to get baptized by John, John says it should go the other way around, but Jesus insists. Jesus gets baptized and the spirit of god descends to him from heaven. A voice from heaven vet's Jesus as the son of God.