Declaration for claiming refund on export of services

Mohammed Aarif V (student of CA) (39 Points)

22 December 2016  

Happy Day Everybody,
For claiming refund of service tax paid on export of service,there should give 
Prior Declaration regarding value, descripttion and quantity
of Input services & output service have to be filed before the date of export of services as per 
Provisions of Notification 39/2012 – ST dated 20th June, 2012.

My question is to whom such declaration is to be filed,and what form to be used to file such declaration and how can we correctly precise the amount of service before the date of export of services?
Thank you for reading,understanding my query and replying the same..