Use ordinary mouse for best result. Orbit model: hold down left mouse-button and pull (around).
In order to move model across screen without orbit (turning the model), hold down shift while orbit.
Zoom model by scrolling (use mouse-wheel).
If you see numbers 'floating' on drawing, you can click them. It's callede 'annotations' and will provide you with, alongside closeup of chosen annotation, information on the subject.