Responsive with child theme

Hi Richie.

I have an issue with child theme. How to activate the responsive.css? I founded a topic about this but I don′t know exactly where to create the functions.php with this code:

add_action( 'wp_enqueue_scripts', 'theme_enqueue_styles' );
function theme_enqueue_styles() {
    wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );
    wp_enqueue_style( 'parent-responsive-style', get_template_directory_uri() . '/responsive.css' );
    wp_enqueue_style( 'parent-rtl-style', get_template_directory_uri() . '/rtl.css' );
}

I tried in the mesocolumn-child directory located inside theme directory (the style.css in child theme works fine) but didn’t work.

Another issue is that even with parent theme I’cant visualize top menu in mobile.

Ok… I was in child theme and then came back to parent but the site isn’t showing in mobile: “He has not found anything. Apologies but no results were found…” But I can see “search bar” and primary menu’s drop down list.

Your theme is all I was looking for and I will apreciate if you can help me.