What is it called when you explain the main events in a story, with who, what, where, when, why, how for each event in order from beginning to end?
What you are asking about is called a summary. A summary is a piece of writing that gives a brief but accurate and detailed description of an entire work, be it a nonfiction or fiction book, an essay, a short story, a speech, or even a scientific paper. Random House Dictionary explains it this way:
A summary is a brief statement or restatement of main points ….
A summary states the main events in order as they appear in the work being summarized. For example, if you are summarizing a postmodernist novel, the author may not write the story in a strict chronological time frame; the author may employ flashbacks and flash-forwards that present what happened before the present time spoken of in the novel or present what may or will happen in the future from the present time spoken of in the novel. This sort of time line would be an unchronlogical time line within an unchronological time frame. An example of this sort of writing is Faulkner’s short story, “A Rose for Emily.” A summary of a work will follow the time line of the actual work being summarized.
Main points will be stated as the who, what, where, when, why, and how of each main event: Who was involved in this main event? What was this main event? Where did it take place? When did it occur? Why did it happen? How did it happen (i.e., reflecting means of action: e.g., “with the candlestick …”) or even how did it come about that it happened (i.e., reflecting motive or cause and effect). These main events will be written about--or summarized--in order of occurrence from beginning to end.