Epigraphs are like little appetizers to the great entrée of a story. They illuminate important aspects of the story, and they get us headed in the right direction.
Instead of a quote or a poem, the novel's prefaced by "An Important Warning." This section is an introduction written by an adult Charlotte Doyle, who's reflecting back on the events of her childhood. Given Charlotte's reference to Susan Coolidge's What Katy Did (1872), the preface can be dated to around 40 years after the events that took place aboard the Seahawk. Charlotte would be a grown woman of at least 53 years old. We are to assume, then, that our narrator is an older and more mature version of the Charlotte from the summer of 1832. The narrative that follows in the remainder of the book is told retrospectively. Why do you think the adult Charlotte chooses this part of her life for her "confession"? Why do you think at this point in her life she feels a need to tell her story?