Welcome to the WordPress Development Environment. This mostly serves as a launching point for larger-scale development inside a container. Please follow the instructions for setup and for information on how to do development here.
To do a manual install go to http://localhost:8080/wp-admin/ and follow the steps in the browser. However, to do an
automated quick install, go into the wordpress container and execute quickinstall on the command-line.
You may need the wp command to make creating a new plugin or other scaffolding in your WordPress development work. Please follow the instructions here to install it.
Then, if you are working on a new plugin, use wp scaffold to generate whatever scaffolding you need and make it a repository of your own if that's your desire, and update docker-compose.yml to make it a volume in the correct location under /var/www/html in the container.
If you are working on a plugin or other piece of WordPress code already existing, check it out and update the docker-compose.yml similar to the other use-case.
A common location you might use is /var/www/html/wp-content/plugins/my-fancy-plugin/ if you are developing a plugin.