Begin with cutting out two rectangles. I made mine 26 by 38 to make it a size small. To get the measurements for your size, measure a dress that fits you will. You will then need fold the top and pin it to create a channel. Mine is about 1 inch wide. Sew each channel
Once you have sewn the channels across the top, you can sew up the sides leaving about 8-10 inches for sleeves. I made a small hem to keep my armholes from fraying. Use a big safety pin to get your ribbon through the channel.
Tie a knot and slide it around so its hidden within the channel. Hem you dress to length and you will have and easy and fast dress and you don't even need a pattern. If you make one, I would love to see yours!