why is the narrator telling the story? To whom do you think he is speaking?

We never come to know who the narrator is talking to in this story, nor, are we told in what way he's telling the story. The first person narration allows Poe to impart the tale first hand by someone who witnessed the action. It's been thought that the narration might possibly be in journal form, although the narrator might just as well be imparting his story to friends or family.