But you don't just want a plain text email. You want a pretty html email.
Set your config file as html:
$config['mailtype'] = 'html';
If you want to pass data (like a username for example) to the html email, put them in an array:
$data = array('name' => $name,
'email' => $email,
'phone' => $phone,
'date' => $date);
Then when sending, point your 'message' to a view. Then pass your data array to it:
$this->email->message($this->load->view('new_user',$data, true));
In your application/view folder create your view.
In this case it's named 'new_user.php'.
You can style this anyway you'd like. Here's a quick example:
<html>
<head>
<style type='text/css'>
body {background-color: #CCD9F9;
font-family: Verdana, Geneva, sans-serif}
h3 {color:#4C628D}
p {font-weight:bold}
</style>
</head>
<body>
<h3>Hi <?php echo $name;?>,</h3>
<h3>Thanks for contacting us.</h3>
<p>You've taken your first step into a larger world.</p>
<p>We really appreciate your interest.</p>
</body>
</html>