There is no definite or absolute way to structure an essay analyzing poetry. In general it is a good idea to begin any essay with a paragraph that states a thesis (that is, a general theme or central argument). One way to organize the rest of the essay would be to move through the poem line by line and even word by word, but this kind of "close reading" works best with short poems. Another way to organize the essay would be to devote a paragraph to each of the kinds of topics you mention. You would want to make sure that each discussion of each topic supports your main argument.
In choosing how to organize the middle paragraphs, you might want to move from the most general to the most specific -- in other words, from the broadest to the narrowest. You might, for instance, want to discuss, in the following order, the topics you list:
figures of speech
Be sure, in your opening paragraph, to indicate that you will be dicussing all or some of these topics. The reader will then know what to expect. Use your opening paragraph as a kind of "road map" to the rest of the essay. Someone once said that effective writing involves creating expectations and then fulfilling those expectations. The opening paragraph gives you a chance to create expectations.
talk about the author, connect elements of the author's life with themes in the poem. like if you were doing an edgar allan poe peom, talk about how poe had a depressed life and how this had an impact on the poems he wrote and how his life impacted his style and the things he wrote about. make connections betweeen the author and the theme and how you interprett it!