WAMP server: Calling a MySQL database through PHP files

I'm currently developing an android application. The backend is written in PHP and takes input from the android app and connects it with a MySQL database (similar to http://www.androidhive.info/2012/01/android-login-and-registration-with-php-mysql-and-sqlite/).

One of my class files (similar to the UserFunctions.java in the above link) requires the url to be given e.g. private static String loginURL = "http://10.0.2.2/android_api/index.php" so that the requisite communcation can take place. My issue is that all my PHP files are in a folder under \www e.g. \www\blah\. I'm fairly sure that I have put my PHP files in the wrong place as the link (Point 2 of http://www.androidhive.info/2012/01/android-login-and-registration-with-php-mysql-and-sqlite/) shows some files being placed in \include\ and the index.php file outside this \include\ directory.

Where should I be placing my PHP files so that my file structure enables my app to communicate with the MySQL database (defined for example as android_api as in the link).