Google Cardboard is a virtual reality platform developed by Google. Named for its fold-out cardboard viewer into which a smartphone is inserted, the platform was intended as a low-cost system to encourage interest and development in VR applications.
Once you have installed the app onto your phone, open up the Google Cardboard app.
The first time you use the app it will ask you to pair your phone with your VR headset. You do this by scanning the QR code that is on the bottom of the VR headset.
Once Google Cardboard has been paired with your VR headset, place your phone into the VR headset and secure the phone inside the VR headset using the velcro on the headset flap.
Hold the VR headset up to your eyes to use the Google Cardboard app. It will start off with an experience called Artic Journey.
When you move the headset around you can see and discover different things. You will notice a white dot in the middle of the screen, you can use this to select things by placing the dot on them and then tapping your phone screen with your finger (there's a screen tap hole on the bottom of the viewer).
There are 5 different parts to the Artic Journey experience: