Hey, Jesse. This actually wasn’t quite what I was looking for, but I may well be able to use it in the future!
But also, I figured out a way to get what I wanted without any coding.
In case you’re interested, I wanted a “Contact” button in a location to the right of the logo in the header, but not where any of the available widgets or menus would have put it.
The work-around I found was to create a new Section, leave it as the very top section, and just set the top margin for the section at a high negative value.
Actually, I have now put two columns in that Section/Row: one for the button on the far right, and one for a kind of byline just to the right of the logo (which is on the far left).
In my case, a Section margin value of -75 put the elements at the same level as the logo, which is what I wanted.
Anyway, all’s well that end well!
Thanks for your helpful responses to my many questions!