Okay, so I need to insert a D.S. al Coda and a Coda section to my piece, but apparently PrintMusic likes to hide the features it advertises, and apparently they release it with ininformative (and broken) tutorial systems, so I have no way of figuring this out. There really is nothing left to do but go make the Sign and the Coda, if I ever find it.

Someone please tell me how to do this!

Use the Mass Edit Tool and Right-click. It should say "Create Coda System".