Denied unemployment, how do I appeal? (St. Louis)

I got a denial letter last week saying I left my job voluntarily, but I was let go as a store manager. It has been a long 22 weeks. My employer's version of events does not match mine, and I have emails that show it. If you have appealed before, what helped you prepare?

Legal aid offices and some workforce centres help with unemployment hearings at no cost. A call is worth it.

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.