I am trying to extend Umbraco forms so that I can store more info that is provided by the Entries table out of the box.

So for example, currently I have a form with a number of fields. These fields will be shown in the entries table. But I want to also add a field that shows which email address was used from the workflow. I can get the workflow email using the WorkflowStorage() class in a custom forms controller, but how do I extend the Entries table to show this? Also, how do I get the record ID of the record that is currently being handled?