Begin at the beginning - that's what they say. In the case of the Bible it's most certainly wise advice. Without a fundamental grasp of Jewish modes of thinking and expression, it is not possible to understand just what Yeshua Hanotzri, aka Jesus Christ, and the disciples were actually talking about! Most Christian church teachings have arisen through combinations of ignorance, credulity...and even deception.
The 'Kingdom of Heaven' is a case in point. It was always an 'earthly' kingdom, to be ruled over by an 'earthly' king! The intent of the infancy narratives in Matthew and Luke was towards the end of proving that Jesus of Nazareth was entitled BY BIRTH to sit on this throne. If he were not, they could not claim - and be believed - that the hoped-for Jewish 'messiah' had come.
According to Christian teaching, this kingdom of heaven refers to some mythical place unimagined by first century Jews. Jesus said that "the Kingdom of God is within you" meaning that every individual, by individual action, owns the power to bring the kingdom into being HERE ON EARTH.