Need Help – > Custom Blog Page.

Hi Experts,
I am new to wordpress and created a wordpress website from scratch. I want to make a custom blog page with blog posts. currently I created a page called blog.php with the following code.

<?php
/*
 Template Name: Blog
*/
?>
<?php get_header(); ?>
<div id="content">
<div id="main">
<div class="textbox">

</div><!--textbox-->
</div> <!--main-->
<?php get_sidebar(); ?>
</div> <!--content ends-->
<?php get_footer(); ?>

I want to show my post inside the div class =”textbox”. currently I am using the following code to show the posts but no post is showing there on the page.

<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
<?php endwhile; else: ?>
<p><?php _e('Sorry, no posts matched your criteria.'); ?></p>
<?php endif; ?>

Kindly help me and suggest me how can I get posts on my blog.php page.

Thanks in advance

Kind Regards
Jarnail Singh