I want to make a dress with that sort of band but i don't know how to approach it. do you have any advice?
I tried to make a drawing of it, and explain the text under the picture:
1: Sew the band with right sides together to the collar of the shirt. I started from the shoulder seam.
2: sew the loose end double with right sides together. till you reach the shirt. turn inside out.
3: turn the part that is sewn to the shirt to the wrong side and sew it like a border/collar (I don't know the word, it turns out like in my picture)
I hope it helps you, like I said before, i am not really good in explaining in English