Hi marks262,
First and foremost, make sure you are using a Child Theme. Once you are using a Child Theme, copy the header.php file of the parent theme over into the Child Theme.
Edit your header.php file as follows:
If you just want to insert that image (without the image being a clickable link):
Look for the following lines:
<hgroup class="fleft">
<h1 id="site-title"><a href="<?php echo esc_url( home_url( '/' ) ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name', 'display' ) ); ?> - <?php bloginfo('description'); ?>" rel="home"><?php bloginfo('name'); ?></a></h1>
<h2 id="site-description"><?php bloginfo('description'); ?></h2>
</hgroup>
Replace those lines with:
<hgroup class="fleft">
<img src="https://tadleyrunners.co.uk/wp-content/uploads/2012/01/TopLogo.jpg">
</hgroup>
If you want to make the link clickable, instead replace with:
<hgroup class="fleft">
<a href="<?php echo esc_url( home_url( '/' ) ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name', 'display' ) ); ?> - <?php bloginfo('description'); ?>" rel="home"><img src="https://tadleyrunners.co.uk/wp-content/uploads/2012/01/TopLogo.jpg"></a>
</hgroup>
Lastly, for either way you choose, remove the background url from the branding element in your style sheet so that the background will blend in with your logo. Add this to your Child Theme’s style sheet:
#branding {
background: none;
}
Hope this helps!