They want proof of why the refusal was wrong, if it was for reason of non-genuine marriage you have to show evidence that your relationship is genuine; proof of all your travel/visits, pictures together, pictures with family, phone bills, chat logs with some good quality conversations, any new evidence since you were refused. In your letter you need to address all of the concerns of the interviewing officer. You should have been collecting this since your refusal in preparation. I believe they want you to make 3 copies? one for the ministers council, one for the iad, and one for you.
As long as it needs to be, you need to go through your blue book that was sent to you, it will have all of the officers notes in there and address everything she was concerned about.
