Denied unemployment, how do I appeal? - any advice?

My claim was denied after 20 weeks of waiting, and the letter says I have a short window to appeal. It has been weighing on me all week. My employer's version of events does not match mine, and I have emails that show it. 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.