How to add a sidebar above the main content, when no occurences of sidebar.php?

I’ve been following a guide on the web to try and add a sidebar to a theme I’ve downloaded.

Heres the guide.

I want to add a sidebar below the header, above where the first post should be on the front screen.

I’ve managed to do this, but rather than add sidebar1.php etc, I’ve had to add conditions into the sidebar.php to show each widget.

At the top of my sidebar.php I have added.
<?php if ( !is_active_sidebar( 'header-widget-area' ) ) { ?>

Then theres the other sidebars…

and at the bottom…

if (is_front_page()) {
		if ( is_active_sidebar( 'header-widget-area' ) ) {

My problem is the other sidebars aren’t showing up. I don’t think its my if statement. I’m not sure what else to try ?