The main purpose of creating phpinfo page is to see what the public (Internet) see to your website. This is a set of php settings for your web server. Here's how to.

1. Create a new text file named as info.php
2. Add this code:
   <?php phpinfo() ?>

3. Upload your info.php to your web server.

Testing: Visit your website, for example http://www.king.net/info.php where I uploaded the info.php file to my main folder normally in public_html.

I hope this help you.