How do you write a screenplay?

Question:The short answer is, with a computer.
the long answer is:

Other then the title page, which contains the title, name of the
play write and contact information, the script itself contains
only 3 elements.

The first line in any script is the slug line. This line contains
information about the scene, whether it is an interior (INT) or
exterior (EXT), the environment OFFICE or FIELD and
whether it is a DAY shot or a NIGHT shot.

The second line is the action line. This is where you
introduce characters and say what they are to do.

Example:
A tall, blond woman, CHRISTINE ATWOOD, walks into the
office.

The next line is Character name, CHRISTINE ATWOOD, in
capital letters.

And the last element is the dialog the character is to say.

The actual format, i.e. top, bottom and side margins can be
obtained by buying an actual script or locating a script on line
and reading it.

There is a lot of script writing software out there, Movie Magic
being one, that you can by but any good word processor
will work. I use Microsoft Word.

Try this site for scripts:

http://www.hunterentertainment.net

go to the Links page and look for Drew's-Script-Orama

P.S.
I almost forgot the most important item, you need a good story

Best Answer - Chosen by Asker: The short answer is, with a computer.
the long answer is:

Other then the title page, which contains the title, name of the
play write and contact information, the script itself contains
only 3 elements.

The first line in any script is the slug line. This line contains
information about the scene, whether it is an interior (INT) or
exterior (EXT), the environment OFFICE or FIELD and
whether it is a DAY shot or a NIGHT shot.

The second line is the action line. This is where you
introduce characters and say what they are to do.

Example:
A tall, blond woman, CHRISTINE ATWOOD, walks into the
office.

The next line is Character name, CHRISTINE ATWOOD, in
capital letters.

And the last element is the dialog the character is to say.

The actual format, i.e. top, bottom and side margins can be
obtained by buying an actual script or locating a script on line
and reading it.

There is a lot of script writing software out there, Movie Magic
being one, that you can by but any good word processor
will work. I use Microsoft Word.

Try this site for scripts:

http://www.hunterentertainment.net

go to the Links page and look for Drew's-Script-Orama

P.S.
I almost forgot the most important item, you need a good story

There's a lot to write about here.
Go to your local bookstore and find a book about screenwriting. Seriously it will make much better sense and they'll give you examples and everything.

Then to save you a headache...go buy Final Draft...it's a little pricey but it will automatically format your script for you. If you do it on say Microsoft Word it will be soooooo tedious!