1.7 Moving custom fields of product to messages section

[Ukleja]

Hi,
How can I achieve that scenario:
1. I add custom fields to the product in the edit section of the product. It is last tab in product edit section. First screen shows the place where I did it

2. I choose the fields on product page like below:

3. When i buy all the items that i want, I want to move those fields in some propper format to the message section in the order which i bought. I mean that place in the BO:



I was trying to find the place, when I click the purchase button ( in the checkout page) I wanted to make a query to the database, and then insert it to the message section. But the problem is, I don't know where to find propper method in the PHP files. I thought that it was OrderController.php, but unlucky. What would you suggest me it that case?