如何正确配置php - CENTOS 6

I am trying to run a simple php code but don't show the message "hello world" you can check here my WEBPAGE.

How can I Configure correctly PHP in my server. I am using centos 6. ??

pd: Before to write this question, I had checked this answer

by running php -v I get:

PHP 5.3.3 (cli) (built: Mar 22 2017 12:27:09) 
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies
<!DOCTYPE html>
<html>
<body>

<h1>My first PHP page</h1>

<?php
echo "Hello World!";
?>

</body>
</html>

below you can check how looks my php.conf UPDATED : Comment the first AddHandler

# PHP is an HTML-embedded scripting language which attempts to make it
# easy for developers to write dynamically generated webpages.
#
<IfModule prefork.c>
  LoadModule php5_module modules/libphp5.so
</IfModule>
<IfModule worker.c>
  LoadModule php5_module modules/libphp5-zts.so
</IfModule>

#
# Cause the PHP interpreter to handle files with a .php extension.
#
#AddHandler php5-script .php
AddHandler application/x-httpd-php .php .php5 .phtml
AddHandler application/x-httpd-php-source .phps
AddType text/html .php

#
# Add index.php to the list of files that will be served as directory
# indexes.
#
DirectoryIndex index.php

#
# Uncomment the following line to allow PHP to pretty-print .phps
# files as PHP source code:
#
AddType application/x-httpd-php-source .phps