Freak said:
I know what your saying. The yeast starter tool is a bit confusing. The best thing to do is just take a 1/2 cup of DME and boil it in a qt. of water for 15 or 20 mins. This should give you about a 1.040 gravity. If it is a bit high because of the boil off, don't worry. You could add some water to it (not too much though) or just start with more the next time. If the gravity is a few points high it wont matter. Let it cool down to 70-90 and add your vial or packet of yeast. It will be just fine. Shake the crap out of it to introduce plenty of oxygen. Put some foil over the top of whatever you are holding it in. In 24-36 hours just stick it in the fridge. Do this about a week in advance to your brew date. You should also look at the recommendations on the yeast company web site. They will likely be close to what I just said but, check first.
The ratio of water to DME for 1.040 gravity is 1/2 cup DME to 1/2 a quart of water. The ratio you suggested is 1.020 gravity, not 1.040 gravity.
http://www.howtobrew.com/section1/chapter6-5.html