Create a file with this code in it:
<?php phpinfo() ?>
Save it as a .php file and call it something like 'checkit.php'.
Now upload it to your server.
Browse to the file. If you placed it in your web root directory, it would be accessed as:
http://example.com/checkit.php
Your detailed PHP settings will be displayed.
The information displayed may be useful to people trying to hack your site, so you should:
1) Save the output and then delete the script; or
2) Protect or hide the script so that others cannot access it.
C Panel users
If you have CPanel, login to your CPanel and all the information is there.