Usually there's a moderator who reads some of this stuff out loud. You go around the room taking turns reading a paragraph. If you don't want to read, just say "pass."
At any time, someone may want to speak up, and they will take a few minutes and comment on their inner spiritual work. Rarely do you hear people say much about their spouses at all. I resisted going to alanon, because I thought, "I'm going to hear my future. I'm going to hear about how bad it is going to get." But that wasn't it at all. People talked about their triumphs, times they resisted depression, or held their tempers.
NO ONE addresses anyone else directly. This is called "cross-talk" and it is strictly forbidden. When anyone speaks, they say their piece, and that is it. Usually the group will say, "Thank you, Mary Lou," or something, but people do not comment on each other's statements.
No one EVER has to say anything. There will never be a time when someone will say to you in front of the group, "Well, Mary Lou, we haven't heard from YOU yet?!?" That will NEVER happen. You couldn't possibly find a more loving and non-threatening situation. When I used to go, I'd walk in the room and just feel buoyed up on an ocean of love. I never said one word out loud. I did see people there that I knew from around town, but everyone is discreet and very respectful of your privacy.
They usually close with the Lord's Prayer; if this is a problem for you, just leave before the end. I used to arrive 10 minutes late and leave 10 minutes early, so I was never even there for the whole hour, and I STILL got SOOOO much out of it.
I think EVERYONE could profit from alanon, whether or not they know an alcoholic. The meetings that I went to were very good. All meetings aren't this good. Just like this board, it depends on the mix of people. I can't imagine that it would ever be a mistake for anyone to go.