So here is tutorial :)
Cut three long strips from a fabric the same length but different widths:
Sew it together :
And then you'll have this :
Pull out one thread and wrinkle fabric....like this:
Fold it and sew and wrinkle in the end..
Now you have this:
Turn it right side up and sew the ends..
And it's done :D
few people have complained that they could not comment on the posts. so just to inform you that the problem is solved :D