WordPress Functions: Show error message in dashboard

functions.php

function showMessage($message, $errormsg = false)
{
  if ($errormsg) {
		echo '
<div id="message" class="error">';
	}
	else {
		echo '
<div id="message" class="updated fade">';
	}
	echo "
<strong>$message</strong>
</div>
";
} 
function showAdminMessages()
{
    showMessage("Welcome to the new WordPress theme.", true);
}
add_action('admin_notices', 'showAdminMessages');