Decide on the money order amount. To purchase a money order, you can go to any United States Post Office location.Instructions for Completing Money Order Inquiry Form. To fill out a money order you need to first fill out the who the payee is, the purchasers information and sign it. A deposit slip must be filled out and submitted with every money order. Make the money order payable to JPay. "Sign your money order only once you are handing it over to be cashed. Signing it beforehand can be risky if it is stolen," says Steiner. All payments must be made in the form cashier check or money order. Print and fill out a marriage record request form.