I have it wrapped around twice as you can see. (I take all my photos with my iPhone --sure is handy :0)
The beauty of this project---it takes only a few minutes to make. There are two steps- cut, then stretch!
These are the two places to cut. Just cut straight across, right under the arm pits, and right above the bottom seem of the shirt. Then take the cut piece and pull it to stretch it. Because of the type of fabric, the edges will simply turn under themselves. You don't need to finish them. Then wrap it around your neck, once, then the second time, making one length shorter than the other.
So much fun, so easy, and a great update to your wardrobe.