You can't do this in either freeware Discus or Discus Professional. Top-level topics can be created only by the board administrator. The board administrator can create new top-level topics using the Topic Manager (or, in version 3.x, the Board Manager).

Our experience has shown that discussion boards are better organized if one individual is responsible for the top-level organization of the board. Users can create subtopics within any pre-established discussion topics that are enabled with the ability to start a new thread.

Historically, Discus was among the first software products to restrict creating and removing top-level topics to an administrator. Since then, most other products have also adopted this model of operation.