I've used several diagram / mindmapping software before and I thought I'd give calligra flow a try.
I can't start my diagram. I see no option to create a text node. I tried insert, enter, double clicking, single clicking, right clicking, I've looked and tried all the buttons and all the menu items. How are we supposed to enter text?

in the stencil box unfold the top heading (the one without a name)
there you will find a text icon. Just drag that onto the canvas

I know how to create a text frame-- but how the heck do I enter text INTO a shape? I've been trying for 30 minutes with no luck.

Double-clicking a shape changes to the 'edit shape' tools. Selecting a shape and then starting to type does nothing.