Attach file to my contact form

I have the following PHP form that works perfectly and I want to add the possibility to attach a file and after 3 weeks of research I still not able to find a way to do.

Please any help will be highly appreciated.

Thanks

HTML CODE:

Code:

<form name="htmlform" method="post" action="MyphpFile.php">
<table width="450px">
</tr>
<tr>
<td valign="top">
<label for="first_name"><b>First Name *</b></label>
</td>
<td valign="top">
<input type="text" name="first_name" maxlength="50" size="30">
</td>
</tr>

<tr>
<td valign="top"">
<label for="last_name"><b>Last Name *</b></label>
</td>
<td valign="top">
<input type="text" name="last_name" maxlength="50" size="30">
</td>
</tr>
<tr>
<td valign="top">
<label for="email"><b>Email *<font size='2'></b></label>
</td>
<td valign="top">
<input type="text" name="email" maxlength="80" size="30">
</td>

</tr>
<tr>
<td valign="top">
<label for="comments"><b>Comments*</b></label>
</td>
<td valign="top">
<textarea name="comments" maxlength="1000" cols="25" rows="6"></textarea>
</td>

</tr>
<tr>
<td colspan="4" style="text-align:center">
<br><br>
<input type="submit" value="Submit">
</td>
</tr>
</table>
</form>





And here is the code of my PHP File:

PHP Code:

<?php if(isset($_POST['email'])) {

// CHANGE THE TWO LINES BELOW
$email_to = "";

$email_subject = "Reporting and issue in UnlimitedWonders";


function died($error) {
// your error code can go here
echo "We are very sorry, but there were error(s) found with the form you submitted. ";
echo "These errors appear below.<br /><br />";
echo $error."<br /><br />";
echo "Please go back and fix these errors.<br /><br />";
die();
}

// validation expected data exists
if(!isset($_POST['first_name']) ||
!isset($_POST['last_name']) ||
!isset($_POST['email']) ||
!isset($_POST['comments'])) {
died('We are sorry, but there appears to be a problem with the form you submitted.');
}

$first_name = $_POST['first_name']; // required
$last_name = $_POST['last_name']; // required
$email_from = $_POST['email']; // required
$comments = $_POST['comments']; // required

$error_message = "";
$email_exp = '/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$/';
if(!preg_match($email_exp,$email_from)) {
$error_message .= 'The Email Address you entered does not appear to be valid.<br />';
}
$string_exp = "/^[A-Za-z .'-]+$/";
if(!preg_match($string_exp,$first_name)) {
$error_message .= 'The First Name you entered does not appear to be valid.<br />';
}
if(!preg_match($string_exp,$last_name)) {
$error_message .= 'The Last Name you entered does not appear to be valid.<br />';
}
if(strlen($comments) < 2) {
$error_message .= 'The Comments you entered do not appear to be valid.<br />';
}
if(strlen($error_message) > 0) {
died($error_message);
}
$email_message = "Form details below.\n\n";

function clean_string($string) {
$bad = array("content-type","bcc:","to:","cc:","href");
return str_replace($bad,"",$string);
}

$email_message .= "First Name: ".clean_string($first_name)."\n";
$email_message .= "Last Name: ".clean_string($last_name)."\n";
$email_message .= "Email: ".clean_string($email_from)."\n";
$email_message .= "Comments: ".clean_string($comments)."\n";

// create email headers $headers = 'From: '.$email_from."\r\n". 'Reply-To: '.$email_from."\r\n" . 'X-Mailer: PHP/' . phpversion();
@mail($email_to, $email_subject, $email_message, $headers); ?>
<!-- place your own success html below -->

Thank you

<?php }
die(); ?> ​