Changing Camera Angle?

Is there a way to change camera view?
I can go up down and forwards, sideways etc, but cant rotate the view.
The shortcuts suggest the "C" key - but this does nothing for me.
Also suggests "Middle click / ctrl + Mouse".
What is that in English?
Tried various options - to no avail.
Anyway - what is Middle Click? I have a left, and right mouse button - but middle?
I can go up down and forwards, sideways etc, but cant rotate the view.
The shortcuts suggest the "C" key - but this does nothing for me.
Also suggests "Middle click / ctrl + Mouse".
What is that in English?
Tried various options - to no avail.
Anyway - what is Middle Click? I have a left, and right mouse button - but middle?