Update — refreshes your screen, which can reveal recently posted Messages. This is the same as clicking your browser's Refresh or Reload button. (When your computer comes back to a Web page it has already seen, it tries to save time by assuming that nothing on that page has changed. So if you or someone else posts a new Message, it might not show up on your screen without refreshing it.)
Contents — displays a Table of Contents, listing everyone's Messages. Click on any entry to read it. The more recent ones are at the top of the list. Each time an entry is indented, it is a reply to the Message above it. (These strings of replies are called "threads.") Here too, the more recent replies are at the top. There can even be replies to replies.
Write — lets you create and post a Message about any subject. Under "Topic" write a few words to describe your particular subject. This lets other people who are interested in your topic find your Message. "From" is for your name. "Write your Message" is space to do exactly that. When you are finished, click "Post Message." If you wish to start over, click "Reset Form."
Instructions — brings you to this page.
Reply — lets you continue the discussion on whatever Message you are currently reading. It works the same as Post, but your Message will show up on the Contents page under the Message you are replying to.
Next — shows you the next Message in the thread of replies, and from there it goes on to the next topic. This can be an easier way to read a sequence of Messages, than going back to the Contents page.
Previous — shows you the previous Message in the thread, but skips over any replies.
Beginning — takes you to the first Message in whatever topic you're reading.