This prompt is asking for you to make a personal, subjective argument. You have to decide whether or not you think that Macbeth is a good example of a tragic hero. Once you have made that decision, then you have to craft a working thesis statement that is going to guide the rest of the paper. Personally, I think the safer option is to argue in favor of Macbeth being a tragic hero. Finding evidence for or against is going to be a similar process, but arguing against his being a tragic hero does make me consider that a portion of your essay should be about a particular character that does fit the tragic hero mold. This would allow you to contrast Macbeth with that character. You are welcome to go that route, but I think it would be more work. The thesis statement in favor of his tragic hero status could be quite simple.
"Macbeth is a classic example of a tragic hero because of his nobility, his flaws, and his final fate."
The four-square method of essay preparation is often used as a graphic organizer that allows students to organize essay "chunks." The four squares in the four-square method are not standardized squares, and the method could be applied to an individual paragraph or the entire paper as a whole. For an essay of this magnitude, I recommend using the four-square method for multiple paragraphs. If the paper is going to focus on the three specifics mentioned in my example thesis, then a four-square organizer could be used for each specific item.
Take a piece of paper, and divide it into four sections. Label the top left box "evidence." Label the top right box "character." The bottom left box should be labeled "quote." The bottom right box should be labeled "summary" or "connection." Above the four boxes, write a simplified version of the thesis. In this case, "Macbeth is a tragic hero." Next, write a sentence or two in the appropriate boxes. The evidence box should contain something about tragic heroes having noble backgrounds. Apply that information to Macbeth in the next box. Then give a supporting quote from the play in the bottom left box. Finally, write a sentence or two that wraps up the entire box. Repeat the process for the other parts of the thesis. These graphic organizers then serve to give you a working framework from which to write the entire essay.