Trouble posting in Sub-Category

You have created a simple page name News from the Admin and displayed under the Blog Menu. You have to create a page template and use the WordPress loop to display your posts. You can use this code in your page template and select templates when you publish the page.

$args = array(    
    'post_type'       => 'post',  
    'order'           => 'DESC',  
);   

$the_query = new WP_Query( $args );   
while ($the_query -> have_posts()) : $the_query -> the_post();   
    php the_title();  
    the_excerpt(__('(more…)'));     
endwhile;

You can pass more parameters to filter your loop as per your need.