1. How to do it?
To use the Cardboard as VR glasses you first have to start the VR mode on your device.
Now select the device you are using.
Next you simply have to insert your phone in the Cardboard and you can start to enjoy your VR movie or photo.
Your screen then will look like on the image below after you activated the VR mode.
2. Where to get Cardboard?
3. What types are there?
There are different types of Cardboards available on the market. Additionally to the different Google Cardboard types, like Cardboard v1 and v2, there is also the ZEISS VR One, a Cardboard model that uses ZEISS precisions lenses and which fits smartphones with a display size from 4.7'' to 5.5''.