Refund of IGST paid on Export of Goods

Hi all,
please tell the steps to take refund of IGST paid on Export of Goods. we have already declared it in 3.1 b column of GSTR 3B and Table 6A of GSTR 1. Is we have to give LUT & Refund application to take Refund. OR GSTR 1 it's self treated as Refund application.
Please suggest the right way to take Refund.

Thanks in advance.