Add category into post permalink

Please go to Settings > Permalinks. Have a look at the Permalinks page for other possibilities.

For You I think you need to use:

/%category%/%postname%

Hope this help!

UPDATE :

For additional slug based on category :

add_filter( 'post_link', 'custom_permalink', 10, 3 );
function custom_permalink( $permalink, $post, $leavename ) {

    // Get the categories for the post
    $category = get_the_category($post->ID);
  if (  !empty($category) && $category[0]->cat_name == "news" ) {
        $permalink = trailingslashit( home_url('news/'. $post->post_name ."https://wordpress.stackexchange.com/" ) );
  }
    return $permalink;
}

Please adjust above code according to requirements for more details please follow this answer or this page