The structure of The Great Gatsby follows Freytag's Pyramid, as most short stories and novels do. First there is Exposition (background information), Rising Action (the problem becomes clear), Climax (highest point of tension and turning point), Falling Action, and Resolution.
The structure also includes flashback. Early in chapter one, narrator begins remembering the story of Jay Gatsby, and from that point forward we are pulled into the past to experience the story.
The Great Gatsby is set in suburban New York City in the summer and fall of 1922, with the introductory section explaining that the main action of the book is a flashback from his 1924 viewpoint. Nick is reminiscing about his time living in the East, trying to bring to some sort of closing the mixed feelings he still carries about the people and experiences he encountered in that tumultuous period.
The story, based as it is on Nick's memories, is told in a fairly straight-forward chronological order. There are some breaks in the action as he jumps from one location or incident to another, but the timeline goes forward in the same general direction. Nick first meets Jordan at Tom and Daisy's home in the early summer; George Wilson kills Gatsby and then commits suicide in November.