The biggest challenge when you begin to write is to get past the notion that things are supposed to look a certain way.
Often, the questions beginning writers ask are: How do I write a slug-line? How do I do a voice-over or a person speaking off-screen? How much description do I give of a place or person? When do I capitalize words, sounds, or names?
Formatting is a skill that can be learned with time. Similarily, it is pointless worrying about how to get an agent or a producer to see your script even before you have one ready to show.
The most important first step is to start writing and start finding the action of your story: Somebody wants something but something is in the way. This is how they try to get around it and either they get it or they don’t. Then what happens?