The best way to start any new language or frame is Hello World.
First the file structure.
What is the app name going to be called. This is not really the fancy name but what your internal app will be called. For example: the main app is called site. For hello world we will call it helloworld.
in you apps folder make a folder called helloworld.
in your new folder you will want to make at the minimal a file called helloworld.php