Lifting plane off another ?

What is the exact procedure for lifting one plane off the other (separating planes). I've watched several video's , video's claims you hold down the control key and "Just" drag the plane off the other. But that's not working for me.

Am I to hold down the left mouse key first then control key the entire drag ? or does the mouse cursor has to be on a entities ?

What is the step by step procedure please.

thank you.

SolidworksGeneral