Social stories are read to a child right before the specified occurrence (activitiy). The goal of the story is to give an explanation to the child of what is going to happen and what is expected of them. Read the story to the child or have the child read it. No further explanation is needed. Eventually, you will see the need for the story decreased as the child begins to understand what is about to occur and what is expected of them. When the child no longer wishes to have the story read to them and they understand the situation, the story is no longer needed.
The following link takes you to an informative article on Social Stories and how parents can use them.