When you are executing TMNav the first time (after downloading and installing it), you see a screen similar to this:

TMNav's main frame

No topicmap is loaded yet, therefore all the views are blank and empty.

Navigate to TMNav's menubar, open the File menu and select the Open topic map-entry.

The following dialog appears:

Dialog to open a topicmap

Use the browse button to select a topicmap (you'll find some sample topicmaps in the doc-directory of the TMNav-distribution) and click OK.

Once the topicmap is loaded, an entry for it is displayed in the Topicmaps loaded - View, which is located in the upper left corner of the TMNav-Frame. The entry shows a little icon depicting a M, which stands for Map, and the filename of the topicmap loaded.

View with topicmaps loaded

proceed -> Using the index view