Wordpress Menu

WP Menu Simple Code
Past This Code functions.php File.....
this is code for one menu
register_nav_menu('id name','Show Name');

register_nav_menus(array(
    'mainmenu' => __('Main Menu','basic'),
    'footermenu' => __('Footer Menu','basic')
));

this is code past menu location...
                wp_nav_menu(array(
                    'theme_location' => 'mainmenu',
                ));


advance Menu System.....
This Is Code Past functions.php
    function theme_menu(){
        if(function_exists('register_nav_menu')){
            register_nav_menu('mainmenu','Andia Menu');
        };
    };
    add_action('init','theme_menu');



    // fall back function
    function menu_fallback_cb(){
        echo '<ul class="nav navbar-nav navbar-right">';
            if(is_user_logged_in()){
                echo '<li class="active"><a class="page-scroll" href="'.home_url().'/wp-admin/nav-menus.php">Create Menu</a></li>';
            }
            else{
                echo'<li class="active"><a class="page-scroll" href="'.home_url().'">Home</a></li>';
            }
        echo '</ul>';
    }
#### This is code past Menu Location.....
    if(function_exists('wp_nav_menu')){
        wp_nav_menu(array(
        'theme_location'=>'mainmenu',
        'menu_class' => 'nav navbar-nav',
        'fallback_cb' => 'fallback_menu',
        ));
}