Hi Peter - welcome here - I'm glad you joined us.
It's normal to be scared to go to your first AA meeting. I think everyone was a bit terrified their first time.
AA meetings in my area start with a chair person welcoming everyone. They ask if there are any newcomers or visitors from another place. You don't have to say you're new if you don't want. Then someone reads the 12 steps. After that the chair person randomly points to a person and asks them to share. If you want to share you say, "I'm <name> and I'm an alcoholic". Everyone will say "Hi <name>" and then you can share about a topic if they have one or anything else you want to say. When you are done everyone will say "Thanks <name>" and the chair person points to another person. Some people say just a couple of sentences while others may talk for quite a bit longer. If you don't want to share, it's perfectly fine to pass. After you introduce yourself you can just say "I pass this evening" and everyone will say thanks to you and the chair person points to another person.
Meetings last about an hour and halfway through we have a bathroom and coffee break and then we start the second half with someone reading the 12 AA traditions. The point and talk format continues until we close.
Toward the end of the meeting they give out sobriety chips for people who want them for 30 days, 60 days, 90 days, 1 year, 1 day, etc. Then we all stand up and hold hands and say the serenity prayer together and the meeting is over.
In my area after the meeting we also do a 1 year cake if there is a 1 year sobriety anniversary. If you are 1 year sober, you can bring a cake and get up to tell your story.