For this day, you'll run the following commands.
here xyz create -t "NPS Data"
This creates a new, empty space with the title, "NPS Data". When it's done, it will output the ID of the new space.
here xyz upload ID_OF_THE_NEW_SPACE -f ./national-parks.geojson
This will upload the data in national-parks.geojson to the space you just created.
here xyz show ID_OF_THE_NEW_SPACE
This will show the contents of the space.