Edit your /etc/pacman.conf file as root:
sudo nano /etc/pacman.conf
Add the following lines at the end:
[dugong-linux]
Server = https://pkg.dugong.dev/repo/$arch
SigLevel = Optional TrustAll
sudo pacman -Sy
sudo pacman -S package-name
pacman -Sl repo-name
To remove this repository, delete the [dugong-linux] section from /etc/pacman.conf and run:
sudo pacman -Sy