If you click on the bold title of a subforum, you will be taken to a page that displays all entries under that topic. Clicking on the title of a topic will take you to a page that displays the text of that topic.
For example, clicking on Introduction brought you to a page displaying a list of topics, one of which was this "Navigation" dialog.
To back up or jump to another area, click on the outline links at the top of the page, just below the logo. For example, this page displays
Board index ‹ FAQ - Frequently asked questions - read only ‹ Introduction
Clicking on Introduction will take you to a list of topics under that title. Clicking on Board Index will take you back to the full display of subforums.