Create an extra Widget Areas in WordPress TwentyTwelve

Question

You can create new sidebar areas by adding the following code to your theme’s functions.php

register_sidebar( array(
    'name'          => __( 'Content Sidebar', 'mytheme' ),
    'id'            => 'sidebar-2',
    'description'   => __( 'Sidebar description', 'mytheme' ),
    'before_widget' => '<aside id="%1$s" class="widget %2$s">',
    'after_widget'  => '</aside>',
    'before_title'  => '<h3 class="widget-title">',
    'after_title'   => '</h3>',
) );

You can change the HTML structure to match your other sidebar and make sure your ID is something unique. Once this has been added you will see a new sidebar under widgets in the admin.

Then to display all you need to do is add:

<?php 
if ( is_active_sidebar( 'sidebar-2' ) ) : 
    dynamic_sidebar( 'sidebar-2' ); 
endif; ?>

To wherever you want the new sidebar to display (usually sidebar.php) making sure the ID’s match.

More information about Sidebars can be found here: https://codex.wordpress.org/Sidebars