Howdy! Umm... let me try to clarify some things...
Apache is a web server application (httpd) and serves web pages.
MySQL is a database that allows you to store/manipulate data.
PHP is scripting middleware that can be used to interact between the two.
In a typical Apache/MySQL/PHP (AMP) set up, you would put your .php files in the Apache root directory with other web pages and access them through a web browser. PHP does not necessarily come with Apache and may need to be installed or activated. You can test this by making a text file called something like "test.php" and putting the following in it...
<? phpinfo(); ?>
If you visit your site, (
http://localhost/test.php or whatever) and you see a PHP report of your configuration, then PHP is installed and working properly. If you see just the <? phpinfo(); ?> code or something else, then PHP is not installed.
By writing PHP code with HTML, you can write code to perform actions, including to read or write data to your MySQL databases. I would recommend also looking into phpMyAdmin as a helpful MySQL management tool.
The error you seem to be getting seems to be some kind of configuration error. If so, you'll have to fix it somehow... maybe changing the configuration line to whatever it's supposed to be or maybe changing something to make the configuration true.
Good luck!
--St