I have followed the MDB Free 'Landing Page' tutorial but I just can't seem to get the heading image to display. The following code block fails to display. Can anyone help me please?

<div id="intro" class="view">
<div class="mask rgba-black-strong">
<div class="container-fluid d-flex align-items-center justify-content-center h-100">
<div class="row d-flex justify-content-center text-center">
<div class="col-md-10">
<!-- Heading -->
<h2 class="display-4 font-weight-bold white-text pt-5 mb-2">Travel</h2>
<!-- Divider -->
<hr class="hr-light">
<!-- Description -->
<h4 class="white-text my-4">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Deleniti consequuntur.</h4>
<button type="button" class="btn btn-outline-white waves-effect waves-light">Read more<i class="fa fa-book ml-2"></i></button>
</div>
</div>
</div>
</div>
</div>