1) Caesar Augustus decreed a census that required everyone to return to their ancestral home. Joseph took a pregnant Mary to Bethlehem, as it was his ancestral home.
2) While in Bethlehem, Mary gave birth to Jesus and laid him in a manger, as there was no room for them in the inn. Shepherds in the fields were visited by an angel announcing Jesus' birth.
3) The shepherds went to Bethlehem and found Jesus just as the angel had said. They spread the word of what they had witnessed, bringing great joy and wonder to all who heard.