 So you just don't understand extrudes. Not a problem. Point extrude just means that if you left click on a point it will create a new point coming from the one you clicked. If you hold control when you do this instead of extruding a new point it's just going to drag the one you selected. If you extrude and press alt you'll be able to change the color of the polygroup for the new faces that are generated. Hope that helps. And as always hope you have a fantastic day and I'll see you around.