"You'll manage rehearsals, actors, technicians, props and costume fittings, and liaise with front-of-house staff and the director. You'll need to have a good understanding of both the technical and artistic elements of a performance so you can ensure it is delivered exactly to the director's requirements."
So basically, a stage manager is like the manager of everything, it's an important job. You'll have to make sure everything is in order and that everything is how it's supposed to be, like the clothing, the place where people will be acting, etc.
For the Stage Manager in Our Town, I wouldn't know as I haven't read the bok.
