Both wordpress website and non-wordpress website run on same domain

Hello Friends in this tutorials i teach you how to run the both wordpress website and non-wordpress website on same domain. There are no file conflicts from the 2 scripts ,so they both go fine on same domain. My main problem is with the index file: i will keep the non-wordpress index.php file ,and have to do something with the wordpress index.php file......

Where do i put index.php from wordpress,in order for it to work ? Other script works perfect because it has it's index.php file .

Here is the index.php wordpress content file : 
<?php
/**
* Front to the WordPress application. This file doesn't do anything, but loads
* wp-blog-header.php which does and tells WordPress to load the theme.
*
* @package WordPress
*/

/**
* Tells WordPress to load the WordPress theme and output it.
*
* @var bool
*/
define('WP_USE_THEMES', true);

/** Loads the WordPress Environment and Template */
require('./wp-blog-header.php');
?>
There will be no permalinks duplicates. And i could use other domain/subdomain ,but i need the non-wordpress as a home , an wordpress to create extra pages with slideshows for clients . So i need the main domain ...for both.