1) You would first need to create a custom field for the product.
-> So in prestashop go to the product edit screen and go to the 'Customization' tab.
-> Select the number of fields you need (3) and update settings.
-> Then for each field, enter the title, for example, Email, Name, Message.
++ Prestashop 1.4: Keep note of the number next to the field
++ Prestashop 1.5: The numbers are no longer shown and the only ways I know of is to right click each field in google chrome and 'inspect element' to get the id of the field, or to look in the database directly:
2) Now you need to connect the customized fields you made to your awocoupon gift certificate
-> go to awocoupon->gift certificates and edit the certificate.
-> Under the personal message section, enter the id's you just created within the product and save.
You have now linked them.
Please let me know if you have any more questions.