I have been promising myself to make a tutorial about this dress because it is so easy. The trick is getting the right fabric--it has to be fabric that drapes well and has small permanent pleats in it. This is often called crystal pleating. It can be hard to find, it goes in and out of style. If you cannot find some in a fabric store, check lingerie, both in thrift stores and in regular stores.
Once you have selected your fabric, cut two equal sized pieces that measure from the floor to the top of your doll's shoulder. Since Bella does not have any pretty dresses yet, she has consented to be my model even though I warned her I would take her hair off. CAREFULLY measure from the hollow of your doll's throat to the middle of her side.
Mark with a pin that same measurement from what will be the top of the dress.
Sew the two halves together from the bottom to where that pin is and stop.
Now make a hand-rolled hem the rest of the way.
Gather the top of the fabric along the pleats. Pull it as tight as you can and tie it off.
Do the same on the other side.