You could set several purposes. What is it about the topic that you need to put into the paper? For example, if it is the Civil War, you might want as your first purpose to learn and write about the major players in the war, such as Lincoln, Grant, Robert E. Lee, etc...
Then, as another purpose, you could learn and write about what each person's part was in how the war unfolded.
Remember, as you begin to fulfill your purpose by answering the questions you come up with, other questions will come up for you, and the knowledge will gel for you in it's own perfect way.
Hope I make sense, if not, let me know, and I'll alter my communication. lol. sorry, I've been listening to mp3's on the presuppositions of NLP.