You would of course want to create a child theme first, so that your changes would not be overwritten when you upgrade the parent theme.
Once you have the child theme, it looks like a simple matter of downloading the /wp-content/themes/magazine-basic/header.php file to your PC and then finding this text using a text-only editor like Notepad (not a word processor, which might introduce extraneous code):
<nav id="site-navigation" role="navigation">
<h3 class="assistive-text"><?php _e( 'Main menu', 'magazine-basic' ); ?></h3>
<a class="assistive-text" href="#primary" title="<?php esc_attr_e( 'Skip to content', 'magazine-basic' ); ?>"><?php _e( 'Skip to content', 'magazine-basic' ); ?></a>
<?php echo str_replace( '</li>', '', wp_nav_menu( array( 'theme_location' => 'primary', 'echo' => false ) ) ); ?>
</nav><!-- #site-navigation -->
<nav id="site-sub-navigation" role="navigation">
<h3 class="assistive-text"><?php _e( 'Sub menu', 'magazine-basic' ); ?></h3>
<?php echo str_replace( '</li>', '', wp_nav_menu( array( 'theme_location' => 'secondary', 'menu_class' => 'secondary-menu', 'echo' => false, 'fallback_cb' => false ) ) ); ?>
</nav><!-- #site-sub-navigation -->
Cut that block of text, then move it just below this:
<div id="drop-down-search"><?php get_search_form(); ?></div>
Save the file, then upload it to your child theme’s folder and you should be good to go.
