Interacting with the model is easy. Let's go over the basic navigation.
Use one finger to rotate or tumble the model.
Use two or three fingers to pan or drag the model, across the screen.
Spread your fingers apart to zoom in.
Pinch your fingers together to zoom out.
While rotating, you might find that the model is not staying centered in your view.
Double tapping a structure will zoom into and center rotation for that object, making it much easier to navigate around it.