include-js.php

<?php

//* Enqueue sticky menu script
add_action( 'wp_enqueue_scripts', 'custom_enqueue_script' );
function custom_enqueue_script() {
	wp_enqueue_script( 'sticky-menu', get_stylesheet_directory_uri() . '/js/sticky-menu.js', array( 'jquery' ), '', true );
}

repostion.php

<?php

//* Reposition the primary navigation menu
remove_action( 'genesis_after_header', 'genesis_do_nav' );
add_action( 'genesis_before', 'genesis_do_nav' );


//* Reposition the secondary navigation menu
remove_action( 'genesis_after_header', 'genesis_do_subnav' );
add_action( 'genesis_before', 'genesis_do_subnav' );

style.css

/*
 * for the primary navigation menu 
*/

.nav-primary {
	position: fixed;
	top: 0;
	width: 100%;
	z-index: 999;
}

/*
 * for the secondary navigation menu
*/

.nav-secondary {
	position: fixed;
	top: 0;
	width: 100%;
	z-index: 999;
}