Once you receive your headset you will find it contained within a protective sleeve. Slide the headset out of the sleeve and simply unfold the unit as shown in the diagram below. You will notice a rubber band near where your phone sits, this provides grip for your phone to ensure it does not slip out.

Google Cardboard V2 Instructions

Scan this QR Code when setting up your headset, it should work with most phones.

And enjoy your Virtual Reality Experience.

Cardboard VR QR Code

Also, a great article on how to Set the Default Viewer Profile in Unity, thanks to the guys at Talesfromtherift!