Piano

Add TTBB and Piano, enter notes, use "Hide empty staves"

This has little to do with explaining music. Enter the first 20 or so bars on all of the staves then use the menu Style->general... then check Hide Empty staves and uncheck Don't hide empty staves in first system. You need to have notes on the staff to prevent it from being hidden, so this only works in continuous view. In page view, you need to wait until the entire score is entered to hide empty staves. It's advisable to enter scores in continuous view anyway because you will always see the last note entered in this view.