I was puzzled. I couldn’t seem to figure out parenting. In Edit Mode, I’d select the second bone, then get of Edit Mode, then Shift-Select the Lower Arm, then Control-P…and then I’d not see “Bone” in the Parent Menu. The only items to select in the mentioned Parent Menu were "Object, Object (Keep Transform), Vertex, and Vertex (Triangle). It was most perplexing.
Alas, the order in which I was selecting parent and child objects was my mistake. All sorted after I watched the thorough instruction again.
Onward!