Add the sample code below to your child theme's functions.php file or in a site specific plugin. Then update as needed and save changes.
<?php
//* Do NOT include the opening php tag
//* Change empty cart messaging for Easy Digital Downloads
function edd_custom_empty_cart_message() {
return '<p class="my_empty_cart">Your shopping cart is empty :(<br /><br /><a href="/downloads/">Return to store to make a purchase</a></p>';
}
add_filter('edd_empty_cart_message', 'edd_custom_empty_cart_message');