Gst refund on freight for exports

Hello,

Kindly advice with the following:

1) Our is a Pvt. Ltd. Company.

2) We made Exports of Vegetables to Gulf Countries in Jan.2018.

3) We paid GST on the Freight Bill raised by the CHA.

4) We would like to claim the refund for this GST that was paid by CHA on Frieght Bill as it is for Exports.

Kindly let us know the procedure and how to move forward with the refund and claim it.

Thanks.

Regards,

Ashish