curtain rises

[user_gary]

The lounge of Jack and Jill's villa at New Hampstead. The essential furniture consists of a table, on whcih are writing materials, and two chairs. As the curtain rises the lounge is empty, but Jack and Jill come in immediately, followed by Aunt Jane.

I know the meaning of Curtain and Lounge but I don't understand as a whole. (particularly because of the word `rises')

[Tdol]

It's the opening of a play- when the curtain rises, the audience can see this scene.