How do I make a room in a house look like a theatre?

Question:

How do I make a room in a house look like a theatre?

I have to make a movie for history.

Best Answer - Chosen by Asker: Are you meaning it needs to look like a stage theatre where actors perform live?
If so, then the thing to think about is "What makes a theatre look as it does?" The legitimate theatre (as it was once known) always has certain elements of design: A seating rake going upward toward the rear; an elevated stage; a proscenium arch; and maybe shell-covered footlights, and lots of seats.
As far as creating the set, I can't help you there, but I can suggest an idea: try using large sheets of cardboard, like from a refrigerator box that's been spread-out, to fashion your set walls and arch. You can also use cardboard for other elements, like a silhouette of some rows of seats, etc.