Basically, your first paragraph is introducing what you may talk about and the essay that you read. You will state in here what sort of rhetorical devices the author uses and the general reason as to why. What I did was devote a paragraph to each rhetorical device and thoroughly explained it in the order of an assertion, then evidence from the story/essay/whatever, and finally elaboration on how it connects to your initial thesis (your thesis is the sentence you wrote on what rhetorical devices and why they were used). Then you conclude your essay going from a narrow sort of topic to a more broad (but don't use a generalization) statement at the end.
This was my basic format when I had to do it. Last years essay was about how I believe satire was used... I'm not sure though. I got a 5 on the exam also.