The listing of the messages can be done in two ways. You can have them as Threaded or UnThreaded. Threaded lists all the messages in the topic, where UnThreaded lists all the subjects and lists the number of messages in brackets next to the subject. To toggle between Threaded and UnThreaded click on "Threaded" or "UnThreaded" below the heading of the current subject.
If you want to post a new message, click on the "Post New" link.
When the messages are listed they are listed 25 at a time. If there are more than 25 messages click on the "Next" link to see the next 25 messages.
Next to each heading of the list of messages in the Topic, there are blue triangles. These allow you to list the messages by the heading. Click on either of the blue triangles to sort. It will stay sorted in your choice until you change it.