Thumbnail support custom post type wordpress.

Create custom post type wordpress

<?php
function create_post_type() {
  register_post_type( 'test_posttype',
    array(
      'labels' => array(
        'name' => __( 'Test' ),
        'singular_name' => __( 'Test' )
      ),
      'public' => true,
      'has_archive' => true,
      'rewrite' => array('slug' => 'Test'),
    )
  );
}
add_action( 'init', 'create_post_type' );

?>

Get URL of current theme/child theme in wordpress

<?php echo get_stylesheet_directory_uri(); ?>

Get theme path in wordpress.

<?php
 echo get_template_directory_uri();
 ?>

Display Menus on Theme in wordpress.

<?php
wp_nav_menu( array( 'theme_location' => 'test' ) );

?>