Cut 2 pieces of bias tape each approx. 60cm/24". Open out one folded edge and starting with a 1cm/3/8" overhang, line bias tape up with raw edge of armhole. Pin right side of bias tape to the wrong side of dress, taking care not to stretch fabric (there will be excess bias tape at the end). Stitch at 6mm(1/4") along the crease. Repeat for other armhole.