Subscribing to that newsgroup will make things much easier for you. You'll be able to update it and get to it quickly without weeding through the whole list. You've subscribed to your movie newsgroup. Now it's time to read what people are talking about. Every time a new topic is raised, a new thread begins.
Every comment related to that topic continues the thread.
Posting your own message can be lots of fun. Just click on New Message and type away. Let's say you're in the Oprah Goes Online community boards specifically in the folder about Web site recommendations. And let's also say you want to start a new 'thread' about superior sites related to the care and feeding of exotic birds. That will tell folks what that thread is about, and they can choose to respond, read, or move along.