Do you mean, "what is an introduction to The Waltz?" I think that a good introduction to the book would be in talking about its themes. Some themes for The Waltz include conformity to social standards (why the narrator finds it difficult to say no to the dance) as well as the idea that love is a disappointment. Parker uses the dance the Waltz as an allegory to twentieth century love and relationships. I think that if you introduce the story by its themes, people will be intrigued in reading the story, or hearing more about it.