You got javascript file and CSS file! Then you have to put those files in you child theme folder like themes -> your_child_theme_folder -> js(if you dont have js folder then create one) and place your js file here AND you have to put you css file in css folder inside your child theme.
Now you need to call js file from functions.php
If you dont have functions.php file in you child theme folder then create it first. Here is the code for calling js file
function wpdocs_theme_name_scripts() {
wp_enqueue_script( 'script-name1', get_stylesheet_directory_uri() . '/js/YOUR_JS_FILE_NAME', array('jquery'), true ); //Path of you js file
}
add_action( 'wp_enqueue_scripts', 'wpdocs_theme_name_scripts' );
In the above code script-name1 is the custom name that you will give to every script you call and the name shud be unique.
And I hope you are already aware of calling css file..