The primary menu in Prospect is called the toolbar. It is a dynamic, toggleable interface that will evolve with our features. You'll notice that certain features are available in scale model mode, and other features only when navigating in the model.
To open up the toolbar:
In Oculus tap the Left Arrow Key on a keyboard or the "B" key on a Gamepad.
In HTC Vive look down at your controllers where it should already be open.