To build your environment you just need to run docker-compose up --build and this will build the following containers for you:
- php
- db
- webserver
You'll need to setup your own DB credentials which you can do by logging into your db container & logging into mysql using root access. You can then setup your own user & update the credentials in your docker-compose file there. For more information on how to do this please look at this Digital Ocean article.
Please note that you shouldn't be including your db credentials in your docker-compose file. Please ensure they're safely stored in your environment specific .env file.
Once built, you should be able to access this at http://localhost.
From here on, you can follow the Laravel documentation.
If you'd like to connect to your db container, please create a duplicate of the .env.example (or just rename it - please do not commit this). This file needs to be called .env.