[isatrader]

I'm so very grateful for this forum, especially this thread. I've found answers to many questions I've been looking for as well as answers to questions I never thought of.
I apologize if this question has been answered already, but I'm a little confused about the momentum index. I've tried building it on stockcharts but I don't understand how I go about creating the zero line. Help!!!

Here's the settings for the Momentum index in stockcharts