Search the Internet for scholarly articles on the debate surrounding the composition and ratification of the Constitution.
These can be primary or secondary sources but should come from academic sources. Recommended sites include: state constitutions drafted after the American Revolution; correspondence from significant colonial figures (e.g., John Dickinson, James Madison, Alexander Hamilton, and others); the Virginia and/or New Jersey Plan; the Federalist Papers, and so on.
These entries will provide a valuable resource for your first historical essay.