Execute docker-compose up -d in the terminal and load http://localhost:8100/ in your browser.
Time to learn some PHP!

Notes
We use port-forwarding to connect to the inside of containers from our local machine.
webserver: http://localhost:8100
db: mysql://devuser:devpass@localhost:9906/test_db
Our local directory, ./php, is mounted inside of the webserver container as /var/www/html/
The files within in our local folder will be served when we access the website inside of the container