First, download and install the Composer dependency manager for PHP.
Next, change into the source directory and install the dependencies:
$ composer install
If you are running PHP 5.4+, you can use the built-in PHP development web server to serve the application:
$ php -S localhost:8080
If you are using a different version of PHP, or want to deploy to a different web server, make sure all it is serving on port 8080, and that all requests are routed to index.php
Navigate to http://localhost:8080 and you should see your first Neo4j application