Simple development question

Hello,

I am somewhat new to drupal and I have a simple development question. I am trying to use a hook to the image gallery module. Specifically, I'm trying to add a gallery through php code. When I went through the source code of the module, I saw this:
> function image_gallery_admin_add($edit = array()) {
> if ($_POST['op'] == t('Delete') || $_POST['confirm']) {
> return drupal_get_form('image_gallery_confirm_delete', $edit['tid']);
> }
>
> return drupal_get_form('image_gallery_admin_form', $edit);
> }

I am confused. Where is the "meat" of adding an image gallery? All it seems to do is return a drupal page.