register sidebar
<?php if ( is_active_sidebar( 'primary-widget-area' ) ) : ?>
<div id="primary-sidebar" class="primary-sidebar widget-area" role="complementary">
<?php dynamic_sidebar( 'primary-widget-area' ); ?>
</div><!-- #primary-sidebar -->
<?php endif; ?>
function blankslate_widgets_init() {
register_sidebar( array(
'name' => __( 'Sidebar Widget Area', 'blankslate' ),
'id' => 'primary-widget-area',
'before_widget' => '<li id="%1$s" class="widget-container %2$s">',
'after_widget' => "</li>",
'before_title' => '<h3 class="widget-title">',
'after_title' => '</h3>',
));
register_sidebar( array(
'name' => __( 'Portfolio Widget Area', 'blankslate' ),
'id' => 'portfolio',
'description' => __( 'The portfolio widget', 'blankslate' ),
'before_widget' => '<div id="%1$s" class="widget-container %2$s">',
'after_widget' => "</div>",
'before_title' => '<h3 class="widget-title">',
'after_title' => '</h3>',
));
register_sidebar( array(
'name' => __( 'Footer Widget Area', 'blankslate' ),
'id' => 'footer',
'before_widget' => '<div class="col-md-3"><div class="prefooter-list-box">',
'after_widget' => "</div></div>",
'before_title' => '<h4>',
'after_title' => '</h4>',
));
}