I have created an example.php:

<?php  get_header();  
 get_template_part('template-parts/banner','title');  ?>

  <div class="container">
    <p>HERE GOES THE TEXT</p>   
  </div>

<?php get_footer(); ?>

in the page-main.php I have created a link:
<a href="<?php echo site_url('/example.php'); ?></a>

When I click it I can see in (page.php/example-php) the header, the footer but NOT the html part. What am I doing wrong?

Please help and thank You for Your help.