Before we start, please make sure that you are not editing /shell-lite/ Theme files directly, if you do your customizations will not be protected when updates are made.

Personal customizations with Child Theme

Now that you have your Child Theme in place, please open /shell-lite/front-page.php and locate the following code on line 37-41:

<div class="grid col-460">

<img src="<?php echo get_stylesheet_directory_uri(); ?>/images/featured-image.jpg" width="440" height="300" alt="" />

</div><!-- end of .col-460 -->

That is where the actual image code is located, if you are changing the image name or the size this is the place to do that.

If you are only replacing the image, just name it the same way featured-image.jpg and save into /shell-child-theme/images folder. Nothing more, nothing less, very simple stuff.

Upload this to your server and you are all done.