It's best to get at least one full script completed and submit it with synopses for the rest. There are conventions about the formatting - line spacing, camera and stage directions - and a lot of companies won't look at it unless it follows them, but there are plenty of books on this. Get a copy of the Writers and Artists Year book for addresses of publishers, companies and agents. Some companies will only accept submissions through an agent. The book will give you a lot of help on this, and libraries always have copies. Then just keep sending it to companies. It's not unusual for commissions to be given to unsolicited sources, but be prepared for box-loads of rejections.