Well, certainly if you are going to examine Poe's skills as a story teller you need to think about how he is so successful in creating stories of horror with richly symbolic settings that dominate the tale and also characters that stick in the mind a long time after the tale is finished. His use of symbolism, as in "The Masque of the Read Death," really is very powerful indeed and manages to suggest so much by saying so little.
There are a myriad of sources that will provide you critiques of Edgar Allan Poe's talent as a story writer, and as a poet. In many ways, he is unsurpassed in poetry, and in storywriting he is the benchmark for the horror and mystery story.
Poe himself contended that a short story must have a singleness of purpose, and, indeed, his narratives follow this rule. In so doing, however, Poe uses what he terms arabesque; that is, he has various turns and returns to the single idea of his plot. For instance, in his famous "The Cask of Amontillado," Montesor does not simply deceive his victim Fortunato in leading him into the catacomb. Instead, he winds the man through rooms and through various mental conditions, all of which toy with him more and add to the suspense with a crescendo until the final revenge is exacted.
The first thing you need to do is set up your essay. Depending on how many points you want to make about him and his writing, that's how many body paragraphs you will want. In the introduction, introduce him as a writer, where he's from, some of his more famous works, and then your thesis statement (last sentence in your intro paragraph) will most likely list out his attributes that you will be talking about in the body paragraphs.
Use his biography link to find some main points about him that make him such a great writer. Divide these points up into the body paragraphs. Some points you could make about him are his ability to draw his readers into his dark mysteries, his impressive vocabulary usage, and his ability to singularly focus on the central character in his stories. He is the reason we have both short stories AND murder mysteries today. He opened up both of those genres for all of writing. After you develop those paragraphs, then close the essay with the conclusion. Good luck!