how to make parallax scrolling website using bootstrap

<style>
.parallax { 
  /* The image used */
  background-image: url("img_parallax.jpg");


    /* Set 
a specific height */
  height: 500px; 

  /* Create the parallax scrolling effect */

    
background-attachment: fixed;
  background-position: 
center;
  background-repeat: no-repeat;
  background-size: cover;
}
</style>

<!-- Container element 
-->
<div class="parallax"></div>