Cortona will start automatically when you open a file containing VRML world. There are two parts of the Cortona window:

Toolbars:

The vertical toolbar, which contains buttons used to specify navigation type in a Virtual City.

The horizontal toolbar, which contains buttons with predefined actions to change your position in a Virtual City.

For a more detailed instruction on how to use the tools, right click on the Cortona window and under help, select user's guide. Then select the appropriate section that contains the description of the Cortona main controls.