Because William Faulkner's "A Rose for Emily" is not written in chronological order, you may first wish to organize the main events into this time order. That is, Faulkner starts and ends his narrative in the present, the now of the story, while the three middle sections parts II, III, and IV) detail the past. The author does this in order to prevent readers from putting "all the pieces together," thus increasing the Gothic horror of the discovery at the end of the story.
Thus, the narrative of the past begins in part II; however, even this part is not in chronological order as it begins with reference to the strange odor around her house that the townspeople detect after Homer Barron departs. Then, the mention of her father's death is made.
Perhaps, a good way to organize the main events is by finding all the deaths that are involved in the narrative; for, Emily is surrounded by death: first, her father's death, then her refusal to release the dead body of this patriarch; after this, she withdraws from society, then she meets Homer Parton, and so on. If you will organize the order of events in the three inside sections in time, you can find the main events. And, again, as a way of introducing your essay, you may wish to mention that Emily is always surrounded by death in her life.
As another aid to your understanding of the main events, see the links below which provide the summary of Faulkner's remarkable story.