pdf certificate generation

Hi,
I'm trying to generate a user specific pdf certificate once a form has been completed.

I understand (from reading "PDF Generation Add-On" topic) that using the (?action) hook 'gform_after_submission' will access my form data at the right point to pull the data out.

I'm trying to figure out how to pull the data out!
Would the basic code be something like:

<?php
do_action ( 'gform_after_submission', $function_get_my_data_out )
?>

Then send the data in array form to the pdf generator.

- is there anyone out there who knows how to do this?

Grateful for any help.

Very helpful, thank you David.
A quick question:
Can I clarify that "entry creation" mentioned in the link means that the data has been entered into the relevant SQL database? In other words the form input has been saved in the database by the time the hook 'form_after_submission' is called?

Great thanks for the speedy reply Chris,
From following the previous reply links, I understand that the form data can be accessed via the $entry object.
So my guess for the syntax would be:

add_action ('gform_after_submission' , array ( 'className' , 'methodName' ) ;

or more specifically:

add_action ('gform_after_submission_my_form_id', array ( '$entry', 'method_pull_out_my_data' )) ;
  function ('method_pull_out_my_data) ;

Does that look about right?