In your cover letter this time, be sure to talk a bit about your experience doing research and development your argument through research: where were your stumbling points? how did you get through them? who/what helped you?
In addition, describe in some detail how your meeting with your writing group went, and how you’ve used their feedback. You should be certain to include an acknowledgments with this essay, as well; it’s customary for it to appear just before the list of works cited, or just before the foot- or endnotes.
Otherwise, you know the drill: assess and reflect on your essay.
that’s clearly supposed to be “developING an argument.” My apologies for the typo.