To address your specific question, you will file a Calif 100S. See the attached Calif Franchise Board discussion on this about 3/4 of the page down.
http://www.taxes.ca.gov/corps.shtml
This of course assumes you have made the appropriate federal filings and elected to be an LLC taxed as an association and then made the S election.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
