Final Draft has several theater templates built in. Go to File > New from Stationery. Select Scripts. You'll see your options for stageplays.
Keep in mind that all Final Draft templates are extremely customizable so if you need different margins, font, etc., you can design your own template.
IMPORTANT: Live technical support (phone, chat, email) for Final Draft 8 has been discontinued. You will still be able to find information and solutions in this knowledge base and in the FD8 User Guide.