Denied unemployment, how do I appeal?

My claim was denied after 15 weeks of waiting, and the letter says I have a short window to appeal. 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?

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

Thanks for writing this out. I went through something close to it 3 months ago, and it got easier once I kept a simple log of every call and form.