Screenwriting is a process in which you think for a long time and write in a short time. The thinking portion of our journey has concluded and the writing is about to begin. As you know a screenplay is made up of sequences of scenes and each scene’s anatomy includes a slugline, action, character names, and dialogue. You can use shots too, but I don’t recommend it in most cases. For starters, the reader only sees what you describe anyway, so there are subtler ways to suggest how somebody views a scene. Also, the director is the one who ultimately determines the shots so, personally I like to concentrate on my job without including directions like that. That also goes for parentheticals that tell how an actor should read a line. Unless it’s very ambiguous and can make a big difference in the scene, I don’t split hairs.
Screenplays are formatted in a specific way and if you can afford it, it is a good idea to get a screenwriting program like Final Draft, or Movie Magic Screenwriter that formats for you and remembers scenes and characters. You can also download celtx for free. If you want to just use your current word processor you can get the margins and other formatting info here.