Appeal deadline questions after an unemployment denial - any advice?

My claim was denied after 12 weeks of waiting, and the letter says I have a short window to appeal. This is my first time dealing with any of this. The letter lists a deadline and a hearing process, but it is hard to follow. If you have appealed before, what helped you prepare?

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