Choose an existing skirt to use as a size guide. Use a measuring tape to find a measurement for the waistband and the appropriate length.
Use the length measurement taken in Step 1 to cut the tulle into five pieces of the same length.
Sew a gathering seam into the top edge of one piece of tulle. The top edge will eventually become the waistband of the tutu. Use a 1-centimeter seam allowance. If you're using a sewing machine, don't backstitch at the end of the seam.
Pull the thread gently to gather the tulle. Be gentle to avoid breaking the thread. Create gathers in the tulle as you go. Continue gathering until the sewn side measures the same length as the waistband measurement that you took in Step 1.
Sew over the gathering stitch after you have properly adjusted the gathers in the tulle.
Repeat Steps 3, 4, and 5 until you have used all the pieces of tulle.
Pin the five pieces of tulle together.
Sew the five layers of tulle together.
Fold the ribbon in half and iron the crease.
Unfold the ribbon and pin it over the waistline so that one side covers the outside seams and the other side covers the inside seams. There should be about eight inches of excess ribbon on each side of the tutu. Sew the ribbon to the tutu by stitching along its bottom edge.
Place the tutu on your child and tie the ribbon waistband securely to keep it in place.