To install json-glib, run the following command in macOS terminal (Applications->Utilities->Terminal)
sudo port install json-glib
To see what files were installed by json-glib, run:
port contents json-glib
To later upgrade json-glib, run:
sudo port selfupdate && sudo port upgrade json-glib
Reporting an issue on MacPorts Trac
The MacPorts Project uses a system called Trac to file tickets to report bugs and enhancement requests.
Though anyone may search Trac for tickets, you must have a GitHub account in order to login to Trac to create tickets.