How to make the 'Header' appear on every page?

You could take the header off the home page and you effectively have a header on every page.

add the header image to the header.php file, the header.php file is included in all pages

No! Do not edit the theme itself. First create a child theme for your changes.

Sorry eddmash, may be a stupid question, but how would i do that?

knoppys – the image below that is there now – on the blog pages sits below the date and page title which is not what i want – obviously i want it above this.

you will have to create a child theme incase you update it doesnt delete the changes you make,

i don’t have the theme your using but you should find the following file two files header.php and front-page.php

go inside the front-page.php file and find header_image() function.
cut the whole code section this function dependent on probably it will be something like
<img src=”<php header_image();>”>

and move it to the header.php

I don’t have a front-page.php

do you have home.php and index.php ??

not a home.php but yes an index.php, where i can see: get_header(); ?>

do you have a templates folder or page template or something similar

I use a custom CSS plugin

You will need to create a child theme for these changes.

This theme already has an installable child theme. In the theme itself is a folder named “child-theme” and inside that is a child theme that you can install.

I created the theme to have the WP header show just on the front page but you also have the option to add the image to the other pages using the banner widget position.

If you use the child theme to make the modification, you can copy the sidebar-header.php over to the child theme, then remove the php code inside this container:

<div class="row-fluid">
</div>

Replace it with this:

<?php if ( is_active_sidebar( 'banner' ) ) : ?>
<aside id="lum-banner" class="span12">
<?php dynamic_sidebar( 'banner' ); ?>
</aside>
<?php endif; ?>
<?php $header_image = get_header_image();
if ( ! empty( $header_image ) ) : ?>
<aside id="lum-wpheader" class="span12">
<a href="<?php echo esc_url( home_url( '/' ) ); ?>"><img src="<?php echo esc_url( $header_image ); ?>" class="lum-header-image" width="<?php echo get_custom_header()->width; ?>" height="<?php echo get_custom_header()->height; ?>" alt="<?php bloginfo('name'); ?>" /></a>
</aside>
<?php endif; ?>

thank you!