how can add menu and sub menu on wordpress admin area plugin creation

add_action('admin_menu','travel_admin_menu');

function travel_admin_menu() {
 add_menu_page("Test", "Test",3,
  __FILE__,
  "wp_test_page",
  Test_PLUGIN_URL."/images/test.png"
 );

 add_submenu_page(__FILE__,'Site list','Site list','3','list-site','pro_admin_list_site');
}