Make a script work within a page

I think both external CSS & JavaScript files should be added to your active theme functions.php file into function which implements action wp_enqueue_scripts.

It should looks like example code below:

<?php
// ...
function themename_enqueue_scripts() {
    // ...
    wp_enqueue_style('themename-slider-style', '//scd01.bcnshop.com/ca/widgets/generate-css/1815/4150.css', false );
    wp_enqueue_script('themename-slider-js', '//scd01.bcnshop.com/ca/widgets/generate-js/1815/4150.js', array('jquery') );
    // ...
}
add_action( 'wp_enqueue_scripts', 'themename_enqueue_scripts' );