You will meet the leader and fill in paperwork. You will then get weighed and they will set you your first goal. You should then stay t the meeting (at least the first time anyway) and your leader will discuss tips and receipes with the group. This is what happened at my 1st meet anyway.
I was really nervous but I went on my own and it really isnt that bad. Everyone is in the same boat so you wont feel alone.
Good Luck xx