Got a denial letter for unemployment, what now? (update)

I got a denial letter last week saying I left my job voluntarily, but I was let go as a production planner. I have read a lot of threads here and could not find my exact situation. The letter lists a deadline and a hearing process, but it is hard to follow. Did you bring documents or only talk?

File the appeal before the deadline, even if you are unsure. You can gather documents afterwards. That is the one part I would not wait on.