New to screenwriting? The Hollywood Standard tells you how to format a script. Final Draft is a software program that helps you format a script. Once you learn formatting and digest the required reading, you'll be good to go. (Actually, you may want to begin outlining and writing small sections while you read.)
FormattingRiley, Christopher. The Hollywood Standard, 2nd Edition (Studio City: Michael Wiese, 2009).
Required Reading(In This Order)Snyder, Blake. Save The Cat! (Studio City: Michael Wiese, 2005).
Suggested ReadingAkers, William. Your Screenplay Sucks! (Studio City: Michael Wiese, 2008).
StoresThe Writer's Store in Los Angeles has nearly any resource you could ever want.