How to take the train at Brussels airport?

In this HIHTAST tutorial you will learn how to take the train at Brussels Airport. No fast-fast tutorial but a tutorial that shows every step.
It's very easy to take the train at Brussel Airport in Belgium.
You can go fast and cheap to the city center of Brussels, to Ghent, Ostend, and so on.
Look to the other tutorial how to buy a ticket.
Enjoy!