Luke 2:16-20

Luke 2:16 (KJB)
And they came with haste, and found Mary, and Joseph, and the babe lying in a manger.

Since the shepherds did not know exactly where the baby was, they had to make diligent search until they finally found the place where He was. They then went in and saw the baby lying in the manger. They no doubt told Mary and Joseph about the heavenly visitors they had and how they lit up the night sky. The fact that they found the babe lying in a manger was a confirmation to them that they did indeed receive a divine visitation.

Luke 2:17 (KJB)
And when they had seen it, they made known abroad the saying which was told them concerning this child.

Once they had seen the babe and the parents, after they left, they began to spread the message about what they saw in the night sky and the baby Jesus. These shepherds were the first evangelists. Their message had consisted of what was told them concerning the child. The Savior had come to Israel and that was the center of their message. They may not have been the most astute theologians, but they were getting the message out in their own way.

Luke 2:18 (KJB)
And all they that heard it wondered at those things which were told them by the shepherds.

Once the shepherds started announcing the birth, the people were stirred up because they wondered at those things they heard. They all knew of the promise of Messiah and now they were hearing that He was born in Bethlehem. They proclaimed Jesus as the messianic fulfillment of the angelsí message. The people would have been wondering since the messengers were shepherds, Jesus was born in a stable to poor and humble parents, His bed was a manger. How could the Messiah of Israel be born into those conditions?

Luke 2:19 (KJB)
But Mary kept all these things, and pondered them in her heart.

Mary was not sure yet of all the things that she heard so she pondered or considered all the things which she heard. Just like when Joseph dreamed the dream that he was someday going to rule over all his brethren, Jacob was not sure of what that meant, so he didnít reject it, but kept the saying for a future time. (Gen 37:11 KJV) And his brethren envied him; but his father observed the saying.  Sometimes we come across information long before we will ever use it. Jesus had told his disciples even early in His ministry that He was going to be killed and they did not heed it, until the events started to unfold. Mary too kept the sayings in her heart and some day, they would come to pass and she would remember them.

Luke 2:20 (KJB)
And the shepherds returned, glorifying and praising God for all the things that they had heard and seen, as it was told unto them.

Then once the shepherds had finished bringing message to the small town, they then returned to their flocks. It was a return journey of praise and glorifying God for the things which He had showed them. While socially, many thought shepherds were low class but here God gives the first announcement of the birth of Messiah to them which raised their joy and praise level to the highest.