Your introduction should be five to ten pages long. The choice of topics is up to you, although I've listed suggestions below. Undergraduates might particularly focus on a few essays or essayists, doing close readings rather than grappling with the larger genre questions. Graduate students should strive to fit this paper into the ongoing professional discussions about the essay. Or, choose a couple of writers who seem to be writing for very different readers.
Some essayists are involved in the scene of their essays, others are more observers.
Discuss how you can tell the difference and what this might mean. Discuss the interrelations and affects of several essays published as a volume. One traditional comment about the essay is that it's digressive. Pick some essays that strike you as quite digressive. Explain it so that someone who hasn't noticed the strategy can see what it its and understand its significance.