Maybe someone else will chime in to provide an exact step-by-step, but in the meantime, here are some things you can play around with. Try it on a copy of the document first.
(1) Turn on View: Extras: Show Text Threads. This way, any time you click (with the black arrow tool) on a text box, you'll see the path of text into and out of the box.
(2) If you click *once* on the out-port at the bottom right of a text box, you will break the text thread (and you will see a little red plus sign indicating that there is overset text).
(3) If you click *twice* on the out-port, your cursor will “load” with text (you'll see a tiny text-box icon), and that text will flow into whatever box you click next.
(4) If you loaded your cursor by mistake, just hit Escape and it will unload.
Exactly how to use this information to get text to flow correctly from 47 to 48, and from 37 to 38 to 39, is still a slight mystery to me and I don't want to steer you wrong. But maybe this will be enough to get you going for now.
Good luck from a fellow green person.