So How we can make such type of links in our post. We can do it two ways, First when we write our Post there is insert more tag option as you can see in above picture.
But sometime a person forgot to add it manually, so how we can insert this tag automatically on every post of WordPress.
In theme twenty elven of WordPress just go to indext.php file and just see this code
<?php if ( have_posts() ) : ?>
<?php twentyeleven_content_nav( ‘nav-above’ ); ?>
<?php /* Start the Loop */ ?>
<?php while ( have_posts() ) : the_post(); ?>
<?php get_template_part( ‘content’, get_post_format() ); ?>
<?php endwhile; ?>
Now In Place of <?php get_template_part( ‘content’, get_post_format() ); ?> just past this function <?php the_excerpt(); ?> and then see the behaviour and you will see the continue reading link.