adding css and js files using action hook
function add_theme_scripts() {
wp_enqueue_style( 'style', get_stylesheet_uri() );
wp_enqueue_style( 'slider', get_template_directory_uri() . '/css/slider.css', array(), '1.1', 'all');
wp_enqueue_script( 'script', get_template_directory_uri() . '/js/script.js', array ( 'jquery' ), 1.1, true);
if ( is_singular() && comments_open() && get_option( 'thread_comments' ) ) {
wp_enqueue_script( 'comment-reply' );
}
}
add_action( 'wp_enqueue_scripts', 'add_theme_scripts' );