You're dealing with human nature. Most people are uncomfortable talking in front of crowds, and they only become good at it after many years of training and practice. Step one is to remind yourself that the members of the class are rooting FOR you, not against you. They, too, will be (or have been) in the position of "presenter," and they sympathize. Second, focus on the facts of your presentation. You have some important things to say. Third, remember that nobody expects perfection. This is a "history" class, not a course in speech communication. If you had spent six months learning about debate techniques and practicing giving speeches, that would be one thing, but in fact the class has been studying history, and that's entirely a different matter. Nobody expects "academy award" performance, or "extravaganza" presentation. You'll be a little nervous, which is normal. But concentrating on making sure the points of your speech are clear, explaining thoroughly, and keeping focus on facts, rather than on you, and "how you are coming across," will go a long way toward improving your level of control.