Many thanks for the helpful reply – the plugin I was looking at came with a warning that it hadn’t been updated recently enough to be secure, so I was taking it more as a promising sign that solutions were out there, than as useful in itself.
I’m using the Genesis Executive Pro theme – I should also say I’m very new to this – I’ve been editing websites and hiring developers for years, but this is my first go at putting together something basic from scratch for a friend (it’s: https://admiraltybar.org/).
I’ve found functions.php for the theme – do I just dump the extra bit of code at the bottom and save it, or does it need to go anywhere special?