Theming marketpress with upfront

Hello, I am trying to create mp_product.php and mp_category.php files inside my Spirit theme. However, I couldn't locate the page.php file from which I can modify and place the marketpress loop. I realize, however, that the default behavior when viewing a product under upfront theme is through the Blog Page template (page_tpl-blog.php).

 * Template Name: Blog Page template
 * @package WordPress
 * @subpackage blog

$layout = Upfront_Output::get_layout(array('specificity' => 'archive'));

echo $layout->apply_layout();

However, this is not the ordinary kind of page php codes I have seen before, I am not sure where I should place the marketpress loop. Any help would be much appreciated.