For a quick look at some of the basics of proper playwriting format head to this page: http://www.playwriting101.com/ All of the playwriting formatting I know, I learned in a playwriting class in high school but this site seems to have a pretty good handle on the whole process. There are a few forms of formatting for stage plays in the U.S. and this site offers a rundown of a few of the most common:
If it’s screenwriting that has peeked your fancy then check out this link. This site gives you a sample page of screenplay formatting and shows you the required steps. http://www.writersstore.com/how-to-write-a-screenplay-a-guide-to-scriptwriting/
However, if you’re submitting your screenplay for publication then you should refer to the publishing house you’re interested in for their formatting requirements. Have fun and if you have any questions be sure to contact me!!