How to display the material tab? I don't have a material tab in blender, like this one (the globe): 

https://youtu.be/ITfkvQdWaRA?t=489

This is what I have: 



How do I make it appear?
That's because you probably don't have selected your object. Select your object by right-clicking it and then it should appear the awaited tab.

In your case right-click the ground.