how to place an lock icon over an image on another css code example

Example 1: css how to place an icon on a photo

<link href="https://use.fontawesome.com/releases/v5.7.1/css/all.css" rel="stylesheet"/>

<div class="container">
   <img src="https://placekitten.com/300/300">
   <a href="dog.png" download="new-filename"><i class="fas fa-download"></i></a>
</div>

Example 2: add image icon bootstrap

<div class="text-center">
  <img src="..." class="rounded" alt="...">
</div>