Travel to your school's library, or the closest university library, and search their catalog system for the topic you wish to write a report about.
Write the titles and call numbers of every title that looks relevant. You should start seeing the same call number multiple times.
Visit the part of the library that corresponds to the call number you wrote down. If you have no idea where to go, a librarian can help you, or escort you personally.
Read the Table of Contents on several books in the section, and check the books out that look the most relevant. How many books you check out depends on the scope of the report, and how long you have to write it.
Run a search on the library's EBSCOHost or JStore account for your report topic. Most colleges and universities have generous print accounts, so if you can, print out two or three relevant, scholarly articles on your topic.
Read as much of the books and articles as you can. On the index cards, write down insights and questions that occur to you as you read. Always write one note per card, along with the title and page number of the book or magazine that inspired it.
Glance through the notes you made, and think of a thesis statement. A thesis statement is a sentence or two that makes a positive claim about a historical person or event.
Flesh the thesis statement out into a 200-word paragraph.
Write down three reasons why your thesis statement is correct, one or two potential objections, and logical refutations of those potential objections.
Flesh out your reasoning into several paragraphs that present evidence supporting each of your reasons, objections, and refutations. This is the meat of your paper, so how long it is depends on the scope of your argument and assignment requirements.
Write at least a two-page narrative that introduces your topic and gives the reader sufficient background to make sense of your argument.
Write a conclusion that briefly summarizes everything that was argued, and gracefully rest your case.
Write a Works Cited page according to your instructor's instructions. History papers tend to use Turabian citation format. How tedious this will be depends on how well your notes are documented.