Custom attributes (to control the animation of the curtains), Create menu > Locator (what in the world is a locator?), Modify menu > Add Attribute..., Storyboard planning out an animation (of the curtains opening and closing), Animate menu > Set Driven Key (SDK), View menu > Camera tools to get to Tumble, Track and Dolly tools in case you do NOT have a MMB (middle mouse button) or you want to Tumble or Dolly without having to use the Alt key and the mouse together. Using the MMB dragging to remove the curtain controls from their group in the Hierarchy window.
Fundamentals Proj 1-2 Set Driven Key Custom Attributes Editing Custom Attributes Creating Stage Controls Animating the Set