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

My claim was denied after 12 weeks of waiting, and the letter says I have a short window to appeal. Any experience at all would help. I have not done a hearing before and I am nervous. If you have appealed before, what helped you prepare?

Stay calm and stick to facts. Mine lasted about thirty minutes and felt more like a conversation than a trial.

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