— Read some scripts!
Create a free account on ScriptLab.com and find your favorite script and read it. Read some, or read all. It’s up to you. Get a feel for the formatting.
— Go find a quiet place:
and jot down 10 problems you have right now. (too much homework, not enough icecream, dodgy internet connection, etc.)
Now find one that speaks the most to you and find a solution to that problem. This will be the basis of your story.
— Download Sofware and Start Writing:
You can use a free software called, Celtx to write your script or simply use your Google Docs and write out a basic outline. Keep it simple.
Another great scriptwriting software is called Writer Duet. It’s like the google docs of screenwriting.