Silent night, holy night
All is calm, all is bright
Round yon Virgin Mother and Child
Holy Infant so tender and mild
Sleep in heavenly peace
Sleep in heavenly peace
This is describing the scene when Jesus is finally born. He was born in a manger, where shepherds and the wise men came to adore him. The three stars finally join to one, creating a ray of brightness shining on on the Christ, Jesus. "Round yon Virgin Mother" is emphasizing how Mary was conceived with him not through sexual action but through the power of the holy spirit. As most of the people in town are sleeping, all is quiet for little Jesus to sleep. It is nice and peaceful for him to sleep, which is the reason for "Sleep in heavenly peace."
Mary's part of the story was that even though she was a virgin, she conceived Jesus in her womb and gave birth to God's child. Joseph was Mary's husband who aided Mary while she was carrying Christ in her womb. He took care of her the whole way to Bethlehem and walked the whole way their from Nazareth while she traveled on a donkey. The shepherds were there to adore Jesus' presence when he was finally born. A shepherd in Bethlehem also let in Joseph and Mary in his little farm full of animals to stay in, which is where Jesus was born. When the three wise men arrived at Jesus' birth, they gave Joseph and Mary gifts of gold, frankincense, and myrrh.
Jesus of Nazareth was the child of Mary, who was betrothed by Joseph, a descendant of the Biblical King David. Virgin Mary was conceived with Jesus by the power of the Holy Spirit. Jesus is described as the "Christ" of Messiah promised by the Old Testament.
God chose to send Jesus as a baby as it is the lowest of all men but the highest of all kings. It is also human flesh form of God and flesh is sacrificed as an offering. Jesus on the other hand sacrifices himself to save the sins of all the people.