newsletter custom placeholders

Hi Guys,

Front he subscribe page for the newsletter plugin, I'm wanting to collect additional information - ie.

<label>Email<input class="width-50" type="text" name="e" value="<?php echo htmlencode(@$_REQUEST['e']) ?>"/></label>
<label>First Name<input class="width-50" type="text" name="first_name" value="<?php echo htmlencode(@$_REQUEST['first_name']) ?>"/></label>
<label>Last Name<input class="width-50" type="text" name="last_name" value="<?php echo htmlencode(@$_REQUEST['last_name']) ?>"/></label>

I've added the fields to the table, and to the m.php form, but I'm not sure how to inject the data into the table.  is this where the newsletterBuilder-custom-placeholders.php-example comes in?  Can you give me a quick run down on how to use it?