Implement content-nosidebar.php / content-leftsidebar.php

Add this in your functions.php

    if( !function_exists( 'my_custom_widgetize_theme' ) ){

        add_action ( 'after_setup_theme', 'my_custom_widgetize_theme', 10 );

        function my_custom_widgetize_theme(){

            register_sidebar(array(
                'name' => 'My SideBar',
                'id'   => 'my_sidebar',
                'description'   => 'This is the widgetized Side Bar.',
                'before_widget' => '<div id="%1$s" class="widget %2$s">',
                'after_widget'  => '</div>',
                'before_title'  => '<h4>',
                'after_title'   => '</h4>'
            ));

        }

}

//this will be display your side bar

<div class="col-lg-6 col-md-6 col-sm-12">
     <?php if (function_exists('dynamic_sidebar') && dynamic_sidebar('private_event')); ?>
</div>

after you add this code, you’ll see your new sidebar on your dashboard widgets area, there you can drop your menus etc.. wordpress