slemery

I am using PHP for the first time, and will be teaching it soon. I am confused about where to store the PHP files. Our I.T. dept set up Ubuntu 16, with Apache 2.4, and PHP 7.0 I can run the existing info.php from the var/www/html folder and see results using URL http:// IPaddress /info.php I can make html files and store them in ~username/public_html and see results using URL http:// IPaddress /~username/whatever.html But where do I (and eventually my students) store our PHP files? They show as not found if I put them in the public_html folder. And copying new files to the var/www/html folder gives a denied access error. Do I need to get permissions changed so that I (and students) can store to var/www/html? If so, how do I set it up so student A can't see (copy) student B's files? Thanks, Steve