Add items to the dark menu in WordPress

You would need to create a custom post type by adding this code to your functions.php file (only do this if you are comfortable with editing theme files if not you should use a plugin such as “Custom Post Type UI”):

 function custom_post_type() {

    $labels = array(
        'name' => 'Articles',
        'singular_name' => 'Article',
        'add_new' => 'Add New',
        'add_new_item' => 'Add New Article',
        'edit_item' => 'Edit Article',
        'new_item' => 'New Article',
        'view_item' => 'View Article',
        'search_items' => 'Search Articles',
        'not_found' => 'No Articles found',
        'not_found_in_trash' => 'No Articles found in Trash',
        'parent_item_colon' => '',
        'menu_name' => 'Articles'

    $args = array(
        'labels' => $labels,
        'public' => true,
        'has_archive' => true,
        'publicly_queryable' => true,
        'query_var' => true,
        'rewrite' => array('slug' => 'articles'),
        'capability_type' => 'post',
        'hierarchical' => false,
        'supports' => array(
        'menu_position' => 5,
        'exclude_from_search' => false

    register_post_type('articles', $args);

add_action('init', 'custom_post_type');

This is just an example and you should edit the options in the function to what you need from the custom post type. You can refer to WordPress documentation :