Saving custom meta for media upload

Hello,

I have currently added a custom meta field for uploading a media file (image). I can successfully add the upload button to display and work but I’m having problems saving the field when updating the page.

Code I’m using to create and display the field:

<?php
$image = get_template_directory_uri().'/images/image.png';
  echo '<span class="custom_default_image" style="display:none">'.$image.'</span>';

if ($meta)
 {
	$image = wp_get_attachment_image_src($meta, 'medium'); $image = $image[0];
 }
  echo '<input name="image-upload-one" type="hidden" class="custom_upload_image" value="'.$meta.'" />
<img src="'.$image.'" class="custom_preview_image" alt="" />
<br />
<input class="custom_upload_image_button button" type="button" value="Choose Image" />
<br/>
<small>
   <a href="#" class="custom_clear_image_button">Remove Image</a>
</small>
<br clear="all" />
<span class="description">'.$field['desc'].'</span>'; ?>

The above code is from:
http://code.tutsplus.com/tutorials/reusable-custom-meta-boxes-part-3-extra-fields–wp-23821
I can’t find a way to save the input.

I’ve created simple text fields/texttext area fields and can save them no problem using the follow in a save function:

if (isset($_POST['text-two']))
{
   update_post_meta($post_id,'textTwo', esc_attr($_POST['text-two']));
}

Any ideas how I can save the image custom meta field?