The primary menu within Prospect is called the toolbar. It is a dynamic interface from which you can select features. You'll notice that certain features are available in scale model mode, and other features only when navigating in the model.
To interact with the menu, simply use the controller on your opposite hand to point at the icons and select using the trigger on the back of the controller.
For a full and in-depth overview of each of the features available on the toolbar, refer to our feature listing.