Gateway Theme 'Featured' Location

I am working with the Gateway theme and trying to understand the ‘featured’ images under the ‘Featured Posts’ section on the homepage. I see that it is a modular and seems to be populated from user/themes/gateway/templates/modular.html.twig in line 17:

{% if featured %}
<div class="featured-posts">
    {% for row in featured|batch(3) %}
    <div class="row">
    {% for child in row %}

I want to add my own featured images but am unable to find the folder where I can edit these featured posts.

-I did see that the images are stored in the root folder nested in the images folder a few folders down, but that nested folder structure doesn’t mean much to me.
-I also tried using the admin page to see if I was able to edit these posts through there, but haven’t seen those images or any children of that modular type.

I am still fairly new to Grav so thanks in advance for any help! Cheers!

Edit: I did notice in Expert mode that where the Home page references

items: '@self.modular'

But I still can’t find where those modular items might be stored so they can be edited and customized