How to implement PHP validation class.

I'm new to classes in php and am trying to figure out how to use this class:

http://www.phpclasses.org/browse/package/3737.html

If someone could help me get started, I'd appreciate it.

What I'm trying to do is use the required field validator. An example is here:
if (! valid::hasValue(valid::getFormValue("FirstName"))) {
    $problem .= "First name is required<br />";
}

I've done the include, validation.class.php.
And I THINK that where the form says "FirstName" is where I should put the the name of the form field.

Here's a sample of my code:
<?php include("validation.class.php");
foreach ($_POST["badge"] as $badge){ // each badge is one array itself
if (! valid::hasValue(valid::getFormValue("firstName"))) {
    $problem .= "First name is required<br />";
}
$sql = 'INSERT INTO attendeenames (customerID_cart,firstName,lastName,badgeName,email,membType) ';
$sql .= 'VALUES ("'.mysql_real_escape_string ($_POST["customerID_cart"]).'","'.mysql_real_escape_string($badge["firstName"]).'","'.mysql_real_escape_string($badge["lastName"]).'","'.mysql_real_escape_string($badge["badgeName"]).'","'.mysql_real_escape_string($badge["email"]).'","'.mysql_real_escape_string($_POST["membType"]).'");';
mysql_query($sql);
}

Nothing I try in the getFormValue("firstName"))) appears to be working. I've even tried looking at the source of the page with the form and using the ID and the name but neither work.

Here's the source from the page with the form after it renders (the form is rendered so I pulled the source code):
<td><input type="text" name="badge[11][firstName]" size="10" id="firstName11"></td>


I'm wondering if there's somewhere in the class that I'm supposed to set some values for form name or something but I can't find anything.

Best,
MH