You can also logout by exiting your browser. If you do not log off, another person may come along to the computer you were using and be able to access your WebCT account. It is possible that they could view your grades, post messages to the Discussions using your name, check your email, make public or private postings to the calendar, etc. Therefore, you will see only new messages listed in the topic frame - once you've read them, they will 'disappear'. Choosing Return to Discusions from the menu frame will generate a list of available topics in the bottom frame.
Topics are separate conferences within Discussions.
If you have access to a private topic, you will see it listed. If you do not have access to a private topic, you will not see it listed. To access a specific topic, click on the hyperlinked topic title. To determine what topic you are currently in, check the first text line of the top frame. That indicates the name of the topic that you're in.