functions.php

<?php
//to have multiple sidebars in wordpress:
function mytheme_widgets_init() {
	register_sidebar(array(
		'name' => __( 'sidebar1', 'mytheme' ),
		'id' => 'sidebar1-area',
		'description' => __( 'The first sidebar area', 'mytheme' ),
		'before_widget' => '',
		'after_widget' => '',
		'before_title' => '<h2>',
		'after_title' => '</h2>',
	));
	register_sidebar(array(
		'name' => __( 'sidebar2', 'mytheme' ),
		'id' => 'sidebar2-area',
		'description' => __( 'The second sidebar area', 'mytheme' ),
		'before_widget' => '',
		'after_widget' => '',
		'before_title' => '<h2>',
		'after_title' => '</h2>',
	));
	register_sidebar(array(
		'name' => __( 'sidebar3', 'mytheme' ),
		'id' => 'sidebar3-area',
		'description' => __( 'The third sidebar area', 'mytheme' ),
		'before_widget' => '',
		'after_widget' => '',
		'before_title' => '<h2>',
		'after_title' => '</h2>',
	));
}
/** Register sidebars by running mytheme_widgets_init() on the widgets_init hook. */
add_action( 'widgets_init', 'mytheme_widgets_init' );

/**
 * Use a specific sidebar (if it is active)
 * @param string $sidebar the sidebar you want to use
 * @param string $sidebarId the id to add to the sidebar
 */
function use_sidebar($sidebar, $sidebarId){
	if ( is_active_sidebar( $sidebar ) ): ?>
		<div id="<?php echo $sidebarId ?>" class="widget-area" role="complementary">
			<ul class="xoxo">
				<?php dynamic_sidebar( $sidebar ); ?>
			</ul>
		</div>
	<?php endif;
}