Mark 16 is Resurrection Sunday. It is simply told: the women went to the tomb to anoint the body when they got there the body was gone and there was a vision of an "angel" (young man dressed in a white robe). The story seems to end with them in amazement and terror and they went away afraid. Later Jesus appears to them and commands them to proclaim the message of eternal salvation. It is short, it is abrupt and it appears unfinished.
This "unfinished" nature of ending of Mark may explain why later scribes have attached some longer endings and post resurrection stories. Most of the most ancient authorities don't include verses 9 through 20 in the original text of Mark. The stories and text that are in 9-20 seem to be duplicated in the other gospels and are likely authentic stories of the life, death and resurrection of Jesus, what scholars question are the placement of those stories here. Given Mark's propensity for action it would not be surprising to have the Gospel end as abruptly as it began. It began with John the Baptist preaching, it ends in awe and wonder, an empty tomb and some great questions.
These textual difficulties appear in the New Testament on occasion. This passage and the first part of John 8 (the woman caught in adultery) are the longer passages in question. We tend to hold them lightly and to rely on the other extended resurrection narratives for details on the story.
What I am left with is an empty tomb and a big question: so what happened? What did the "young man dressed in white" mean "he is risen"? What happened later in Galilee? We know the story so apparently the women got over their awe and fear and began to tell others.