Add sidebar in wordpress theme

WordPress require 2 steps to use sidebar.

Step 1.Register sidebar

Register your sidebar in theme. add below code in your theme function.php. add widget to your sidebar

add_action( 'widgets_init', 'theme_slug_widgets_init' );
function theme_slug_widgets_init() {
    register_sidebar( array(
        'name' => __( 'My Sidebar', 'theme-slug' ),
        'id' => 'sidebar-id-here',
        'description' => __( 'Widgets in this area will be shown on all posts and pages.', 'theme-slug' ),
        'before_widget' => '<li id="%1$s" class="widget %2$s">',
	'after_widget'  => '</li>',
	'before_title'  => '<h2 class="widgettitle">',
	'after_title'   => '</h2>',
    ) );
}

Your sidebar will be appear in Appearence>Widget menu. add
Step 2.Use sidebar in theme

Edit your theme template where you wish to call sidebar

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