If the page you’re trying to put WordPress things into is in a another folder, you need to change the path so it gets it from the correct place.
If your WordPress installation is in the root of your website then first you need to ‘back up’ out of your folder using:
require('../wp-blog-header.php');
(notice there are two dots at the beginning, not just one). If it’s installed in a folder called wordpress then you need to ‘back up’ then add the wordpress folder:
require('../wordpress/wp-blog-header.php');