Need help with adding custom wordpress menu and sub-menu

Use this code bellow to dynamic you nav:

                        <?php
                            $args = array(
                            'theme_location'    => '',
                            'menu'              => 'Main',
                            'container'         => 'false',
                            'container_class'   => '',
                            'container_id'      => '',
                            'menu_class'        => 'cs-main-navigation cs-clearfix',
                            'menu_id'           => '',
                            'echo'              => true,
                            'fallback_cb'       => 'wp_page_menu',
                            'before'            => '',
                            'after'             => '',
                            'link_before'       => '',
                            'link_after'        => '',
                            'items_wrap'        => '<ul id="%1$s" class="%2$s">%3$s</ul>',
                            'depth'             => 0,
                            //'walker'            => new my_custom_walker_nav_menu()
                            );

                        wp_nav_menu ($args);
                                  ?>
                    </nav>
                    <!-- Search icon show -->
                    <div id="cs-header-menu-search-button-show"><i class="fa fa-search"></i></div>
                    <!-- Search icon -->
                    <div id="cs-header-menu-search-form">
                        <div id="cs-header-menu-search-button-hide"><i class="fa fa-close"></i></div>
                        <form>
                            <input type="text" placeholder="Type and press enter...">
                        </form>
                    </div>
                </div>
            </div>
        </div>

For more details please see This ….. Hope it will solve your problem