Here you can see that I have taken off the printed edges from my fabric. I missed this bit in previous posts. Pin your PF & lining together from the top and sew down either edge. You will have a long tube. Turn inside out, IRON so the two edges are the same. You will then pin the header tape to the top. Sew the header tape along the top & bottom turning about 1cm under at either end of your curtain.
You will have to knot one end of the string in the header tape before hanging and then pull whatever gather you want through it.
And this on the outside!!! There you have it. I am not brilliant at explaining things, but I hope you found this tute helpful, please ask me any questions you want.