Hi Don,
Well, the easiest way to display something there, is usually using custom CSS, something like this:
a.asp_res_image_url::after {
display: block;
content: "Hey!";
color: red;
background: white;
padding: 2px 12px;
position: absolute;
top: 0;
right: 0;
}This will result in this: https://i.imgur.com/eqUUv7q.png
But you will still have to make some sort of changes to the horizontal.php results template file, to include a CSS class on items where you want to display a specific banner, then construct the CSS rules based on those classes.
For the templating, you can check this tutorial.