In general, authors tend to use the following methods, exclusively or in combination. Description presents background and setting. The author tells the story of a series of events, usually presented in chronological order. In a novel however, chronological order may be violated for the sake of the plot. The emphasis in narration, in both fiction and non-fiction, is on the events.
Narration tells what has happened.
Its primary purpose is to tell a story. Exposition presents the facts about a subject or an issue as clearly and impartially as possible. Its primary purpose is to explain. The author uses the techniques of persuasion to establish the truth of a statement or to convince the reader of its falsity. The purpose is to persuade the reader to believe something and perhaps to act on that belief.