Create a custom shortcode for WordPress

// Create Shortcode knapp
// Shortcode: [knapp tittel="" link=""]
function tws_create_knapp_shortcode($atts) {

	$atts = shortcode_atts(
		array(
			'tittel' => '',
			'link' => '',
		),
		$atts,
		'knapp'
	);

	$tittel = $atts['tittel'];
	$link = $atts['link'];

	return '<a href="' . $link . '" target="blank">' . $tittel . '</a>';

}
add_shortcode( 'knapp', 'tws_create_knapp_shortcode' );