If you’re interested in learning more about discussion forums in Moodle, the Forum FAQ is a great place to start. Among the many FAQs you can learn how to enable and troubleshoot ratings, how to customize your site news feed (“site news”), how to enable guests posting, archiving forums and answers/tips for over 20 forum related-questions.
Check it out at http://docs.moodle.org/26/en/Forum_FAQ