How to add a custom post type in wordpress 3.41

Wordpress press-release post type

<?php

add_action( 'init', 'create_post_type' );
function create_post_type() {
    register_post_type( 'press-releases',
        array(
            'public' => true,
            'show_ui' => true,
            'publicly_queryable' => true,
            'has_archive' => true,
            'capability_type' => 'post',
            'rewrite' => array('slug' => ''),
            'menu_position' => 4,
            'supports' => array( 'press-releases', 'editor', 'title' ),
            'has_archive' => true,
            'labels' => array(
                'name' => __( 'Press Releases' ),
                'singular_name' => __( 'Press Release' ),
                'edit_item' => __( 'Edit Press Release' )
            )
        )
    );

?>