This is a dress which you can change the style of .It's based off the Le Sac dress from American Apparel which I have seen people make on Burda Styles. Photos were taken in my bathroom because it's the only place in the house with a long mirror. :P .
The width of the piece of fabric is your bust measurement plus half of that ,so for me it was 76 cm + 38cm .You may want to change it if you want it more flowy .The length can be as long as you like.I made mine above the knee.
Cut the rectangle in half so you have a front and back .
Lay the good sides together and sew up until you get to 6" from the top of the dress.Then use a basting for the 6".
Sew along the 6" bits that has the basting stitch and so it's neat then unpick the basting stitch so the arm hole is done.
Now to make the bit your ribbon goes through.Fold over the top of the dress enough so that your ribbon fits through it.Then sew,sew,sew :)
When you lay it flat ,it looks like this.All you have to do is hem the bottom of the dress
Now attach your ribbon to a safety pin so it's easier to pull through.
That's the dress done .You can put it on in loads of different ways.The web page has a few suggestions(http://store.americanapparel.co.uk/rsa0300.html) or check here(http://www.burdastyle.com/creations/show/28495) .Enjoy !