How do you attach tulle to a dress?

If you are attaching it to the waist of the dress (hopefully there is already a seam to follow!), use thread of a contrasting color to baste it into place, using 1/2 inch hand stitches. Straight pins don't work well with tulle. Then, fold the tulle down and use your machine to top stitch the tulle into place. You can then remove the basting stitches which held it in place.