Chronicles of a Death Foretold is a 1981 novella by Gabriel García Márquez. It is a non-linear story, told from a first-person omniscient perspective, but without the exact details; it is essentially a broad overview with the consequences and killers known, but without the full answers we expect in this sort of story.
To effectively write an essay about this story, you should first have read the book, to fully immerse yourself in the story and give a personal perspective. After that, you can write a thesis statement, which you will then defend or disprove in the body of the essay. Some themes in the novella include personal honor as experienced by the Latin community, revenge as a proper or improper action, and/or gender roles. There is also the unusual narrative structure, which lends itself to multiple interpretations of events.
A 1500 word essay should follow the basic essay structure: Introduction (with thesis), Body, Conclusion, Bibliography -- an Outline might be helpful here, but is not required. For example, you could take the position that the non-linear structure does not help the narrative -- this is a non-typical reaction, as most interpretations take the narrative as a very important part of the story. However, you could say, "By concealing details and telling the story out of order, Márquez intentionally makes the story harder to understand." This is a thesis statement that can be proven or disproven; you may take another stance. Example: "Gender expectations in Latin communities prevent women from taking an active role in matters of justice." Or: "Because of standards of personal honor, revenge is viewed here as a viable solution." There are many positions you could take.
After you have chosen your thesis, you should use examples from the text and possibly examples from other texts to either back up or disprove your thesis. Remember, disproving your own thesis is not a bad thing. If you were to take the position that the non-linear story takes away from understanding, you can quote passages and draw on other non-linear works to show how they are superior or inferior. Remember to properly cite all sources used; use the OWL at Purdue as linked below for formatting questions.
You have a wealth of theme, subject, and style issues to choose from in this particular work. The same basic idea applies to any essay written; make sure to use whatever style your class requires. If you don't have to adhere to an essay-style paper, you could write a short piece of fiction in Márquez's style, or rewrite a portion of the story in a different voice. If you have time, you could also incorporate the film adaptation or the Broadway musical into your thesis.