At first create a single.php files inside your theme folder .

single.php is the single post page, the theme page for displaying just one post.

The single.php is what will be used for a single post page, and most of the code should look pretty similar since we’ve already coded up our index.php.

Example –

<?php
/**
* The Template for displaying all single posts
*
* @package WordPress
* @subpackage Twenty_Fourteen
* @since Twenty Fourteen 1.0
*/
get_header(); ?>

<div id="primary" class="content-area">
<div id="content" class="site-content" role="main">
<?php
// Start the Loop.
while ( have_posts() ) :
the_post();
/*
* Include the post format-specific template for the content. If you want to
* use this in a child theme, then include a file called content-___.php
* (where ___ is the post format) and that will be used instead.
*/
get_template_part( 'content', get_post_format() );
// Previous/next post navigation.
twentyfourteen_post_nav();
// If comments are open or we have at least one comment, load up the comment template.
if ( comments_open() || get_comments_number() ) {
comments_template();
}
endwhile;
?>
</div><!-- #content -->
</div><!-- #primary -->

<?php
get_sidebar( 'content' );
get_sidebar();
get_footer();


If we want we can add comment-template for each post. Just calling the follwing code –
<?php comments_template(); // Get wp-comments.php template ?>