How can I name my location

In Find My you can edit the location name for 'People' and for 'Me' by pulling up the panel which appears when you touch either of those tabs at the bottom of the screen.

You will see the last item is Edit Location Name.

Touch on Edit Location Name and some options appear. You can select from a standard list, a list of those you have previously created, or Add Custom Label - for which you then enter some text.

This choice then appears in Find My as the location (when the iPhone is at that location of course).