I used to wonder this too! Actually what worked best for me was to use the corner of a comb or a pick type comb (even a pen with a cap works). I brush my hair back and then use whatever object to draw the zigzag through (letting it separate your hair) how I want, then carefully pull my hair to the sides and the zig zag is there! Sometimes you have to practice to get it looking right. I tried to do one part at a time and I would always have better results doing it all at once. Good luck!!