function add_my_css_and_my_js_files(){
wp_enqueue_style( 'my-stylesheet-name', plugins_url('/css/style.css', __FILE__));
wp_register_script( 'my-plugin-script', plugins_url( '/js/script.js', __FILE__ ) );
}
add_action('wp_enqueue_scripts', "add_my_css_and_my_js_files");