> I add TicketFreeText at Ticket. Now, I want that this TicketFreeText gets a value from
> my databyse automatically. This value is a unique value in database (number of contract).

Don't think that TicketFreeText is correct. I'd think you'd want to add a new field to hold the contract number data - Customize the customer_user table(http://doc.otrs.org/2.4/en/html/x1936.html).