Tell us how to make all images display a template

The html template looks like this:
div class="card" style="width: 18rem;">
"<"img class="card-img-top" src="..." alt="Card image cap">"
</div>
I need to display all the pictures with these cards, how do I do this?

Read https://learn.getgrav.org/cookbook/general-recipes#creating-a-simple-gallery and modify it to your needs.