I'm secretary for a couple of local voluntary organisations. I'd suggest that you start at now, and work backwards, making sure that minutes of meetings etc (which will be your responsibility) are all there and signed by the appropriate person. Is there a constitution - there ought to be a statement of purpose of the society for any group. Do you know the committee members' names, is it time to review membership?
Is there a Treasurer, or will you fulfil that role as well? That could be a whole different area to look at, if it's you.