What you should do is share your reflections about the course and, in particular, about your experiences writing papers (perhaps you can focus on the research project, but you can definitely also talk about the first two essays). You should talk about what you learned, both in terms of content and in terms of grammar and style, and about the difficulties you faced–and how you overcame them. You can also talk about whether participating in the discussion board activities helped you and whether receiving feedback from your classmates and me was useful. I think that, if you address all of these points, you should have enough to write a good essay. However, feel free to write about anything else related to the course you feel is important to you.
I will also upload the paper you did for me, so you can use it as a reference.