A 3D tour is quite intuitive to use for the "gamer generation" because the keyboard keys used to navigate are the same… but here are a few tips for a newbie.
Generally at the bottom, left hand side of the page of each 3D Tour there are a few simple icons to help you navigate:
The triangular “play“ button will play a Highlight Reel of the digital model, the ruler is a measurement tool (which actually needs further explanation to use acurately), the 3D model takes the tour into "Dollhouse" or context mode, the floorplan lets you see a 2D plan of the floor that you are on, and finally the stacked floors indicate which number floor you are on. To familiarise yourself with the model click each of the icons to discover the details of the space.
Overall Keyboard Shortcuts
If you'd like to impress your client with efficient keyboard navigation here are some keyboard navigation aids:
Now then, feel free to explore with your new-found skills on this example model: https://tours.start2finish.ltd/tour/our-lady-and-st-michaels