Where should i put the code in…??

<?php get_header(); ?>
<div class=”mh-wrapper clearfix”>
<div id=”main-content” class=”mh-content”><?php
mh_before_post_content();
if (have_posts()) :
while (have_posts()) : the_post();
if (is_attachment()) {
get_template_part(‘content’, ‘attachment’);
} else {
get_template_part(‘content’, get_post_format());
}
endwhile;
mh_after_post_content();
comments_template();
endif; ?>
</div>
<?php get_sidebar(); ?>
</div>
<?php get_footer(); ?>

this is the code i copy from my theme(Single.php)

i really have no idea where to put the code in…please..help i am using MH Magazine theme…

https://wordpress.org/plugins/wp-pagenavi/