Silk is such a delicate fabric that some people think it can't be cleaned at home. Dry cleaners can do the job for you, but if you need to use them on a regular basis, it can become expensive. There really isn't any reason why you can't remove a stain from silk yourself. You should, however, be careful washing it and follow the instructions to a tee.
Things you need
Add a little Woolite to the stain and let it sit for a few minutes.
Fill the bathtub 1/4 of the way with lukewarm water while the Woolite is pretreating the stain.
Add 1/4 a capful of Woolite to the bathwater, as well as 2 tbsp of vinegar. Mix the bathwater slightly with your arm.
Place the dress in the water and swirl it around a few times. Don't leave the dress in the water any longer than 5 to 6 minutes.
Rinse the dress for 2 to 3 minutes under cold water.
Set your silk dress on a towel and roll it up. This will get the bulk of the water out.
Hang the dress up on a hanger near a heater so it will dry.