adding new posts into wordpress DB automatically

You can use the wp_insert_post function

   $my_post = array(
            'post_title'    => 'Some titles',
            'post_content'  => 'This is my post content',
            'post_status'   => 'publish',
            'post_author'   => 1,
            'post_category' => array(1, 2, 9000)
            );

            // Insert the post into the database
            wp_insert_post( $my_post );

        }