Creating a modal popup using CraftCMS and Twig

Question

I've been looking everywhere, I'm trying to create a modal using a global but I can't seem to figure out where to start.

JavaScript:

$popUp = new Garnish.Modal($('#popUpModal('),
$popUp.show(),
$popUp.hide()

    (document).ready(function(){
       setTimeout(function(){
         popUp();
      },3000);
  })
);

Twig:

{% set popUpModal = popUpModal.popUpModalContent %}
{% if popUpModal %}
<div class="popUp popUp__popUp-content " id="popUpModal">
    <div id="popUp">
        {{ popUpModal }}
    </div>
</div>
{% endif %}