Denied unemployment, how do I appeal?

My claim was denied after 21 weeks of waiting, and the letter says I have a short window to appeal. Thank you in advance. 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?

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.

I printed my emails in order and wrote a one-page timeline. The hearing officer kept going back to it.