Almost all plays have what is known as a three-act structure:
•    Exposition – including history, foreshadowing, inciting incident
•    Complication – this is the longest section, including point of attack, various complications and solutions until the climax
•    Resolution – short wrap-up
This structure can be divided up into scenes – which is easier for intermission.

Format:
•    Title page with address in the bottom left corner and agent address in the bottom right corner
•    List of Characters with a short description of who they are listed in order of importance
•    Setting description
•    Time description
•    Acts with scenes listed
•    Act 1, Scene 1 and following scenes
•    Act 2, Scene 1 and following scenes
•    Act 3, Scene 1

Here is a good article on screenplay structure for plays from The guardian: http://www.theguardian.com/books/2008/sep/23/writing.plays.screenplays.structure