To install mac-brightnessctl, run the following command in macOS terminal (Applications->Utilities->Terminal)
sudo port install mac-brightnessctl
To see what files were installed by mac-brightnessctl, run:
port contents mac-brightnessctl
To later upgrade mac-brightnessctl, run:
sudo port selfupdate && sudo port upgrade mac-brightnessctl
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.