A good place to start is in the beginning, with the Genesis account in the Old Testament of the failure of the first man and woman God created to perfectly fulfill the plan God established for them. Adam and Eve were put out of a garden of paradise into our world of suffering and pain because of this; But God promised them a Savior who would restore them and all their descendants for all time to God's favor lost by their failure.
That Savior is Jesus Christ who was born just over 2000 years ago in Bethlehem of Judea; this is the first Christmas, the birth of Jesus, the son of God, whose mission was to sacrifice his life on a cross to restore man's favor with God lost by Adam and Eve. Jesus, through his perfect sacrifice is known as the second Adam, because he fulfilled the plan which Adam and Eve did not.
So the real meaning of Christmas is the joyous celebration of the coming of our Savior Jesus Christ. We celebrate his birth given by his mother, the virgin Mary, who was greatly graced by God, in the humble circumstances of a Manger surrounded by the various animals located there. He is visited by shepherds in the field who had been invited to see the newborn babe by a chorus of angels. He is also visited by the Magi, three Kings who had followed a star which led them to the babe in the manger.
Christmas is a time of great hope, that through our love and honor of God, we will share in his plan of peace and fulfillment during our time on earth and afterwards an eternal paradise of no more pain and suffering, but rather an eternal bliss wrapped in the love of God.