WP PHP Form Fields are missing. Where are they? - php

Question

This is a hopeful question. I am really, really PHP inexperienced. But I am trying to teach myself a thing or two. The organization I work for uses a WP site. I regularly work on it. I mostly do HTML and CSS (stuff I know about) but I was just digging around in the background and came across something I don't understand at all.
I made a test page here: http://all4ed.org/webinar-event/test-2/
There are two forms on the page. The first ends in a "submit button," the second ends in a "Register Button."
So far so good. I dug around the backend of the WP files, and found the content-webinar.php file and saw that it pulled the form in as an include with:
// The registration form. ?>
<?php if ($registration_required == 'yes'): ?>
<?php include ('assets/includes/webinar/inc-block-registration-form.php'); ?>
<?php endif;
Good, so far.
I went to the "inc-block-registration-form.php" file and here's where it gets weird:
The first form is done with this code:
<form class="webinar-registration" action="<?= $_SERVER["REQUEST_URI"] ?>" method="get">
<div>
<p>
<label for="token">Token</label>
<input type="text" name="token" />
</p>
<p>
<button>Submit</button>
</p>
</div>
</form>
This looks exactly like I thought it would. The second form is written like this:
<form class="webinar-registration" action="<?= $_SERVER["REQUEST_URI"] ?>" method="post">
<div>
<?php if ($webinars->error) : ?>
<p class="error"><?= $webinars->error ?></p>
<?php endif; ?>
<?php foreach ($webinars->form_data as $data) : ?>
<p><?= $webinars->build($data) ?></p>
<?php endforeach; ?>
<p>
<button>Register</button>
<input type="hidden" name="webinars_registration_submitted" value="<?= $post->ID ?>" />
<input type="hidden" name="webinars_registration_title" value="<?= get_the_title() ?>" />
<input type="hidden" name="webinars_registration_url" value="<?= get_permalink() ?>" />
<!-- fields necessary for AA -->
<input type="hidden" name="webinars_user_id" value="<?= get_current_user_id() ?>" />
<input type="hidden" name="webinars_type" value="<?= get_field('webinar_type') ?>" />
<input type="hidden" name="webinars_post_id" value="<?= get_the_ID () ?>" />
</p>
</div>
</form>
Huh???? Where is the "Your Name", "Your E-mmail Address," "Organization," "City, State," or "Question (This is optional)"
How does this work? Where is it pulling those fields from. Any insight would be appreciated. Thanks.