You can attend that meeting if you are an alcoholic, you have a desire to stop drinking, and you introduce yourself with "Hi! My name is (yourname), and I'm an alcoholic."
My suggestion would be: If they allow you or ask you to introduce yourself, to introduce yourself and then say nothing more than
"I'm new and I need help. Would someone please see me after the meeting."
Closed meetings are only for those that already identify as an alcoholic. If you're not sure -- then, try going to an open meeting first and ask someone there to explain it to you.