how do i have an 'add text field' button for the person entering it

To my understanding, you would like to have a way to add fields to your form when your form respondents click an "Add Text Field" button, is that correct? I'm sorry, however, there is no other button that can be added to Jotform aside from the "Submit" button. 

I would suggest you check out our Configurable List widget and Infinite List widget. Those widgets have a built-in "Add" button where it will add fields to the form if clicked.

To learn how to set up your Configurable List widget, I suggest you refer to this guide: How-to-Set-Up-the-Configurable-List-Widget

I hope this helps. If, in any case, I have misunderstood your concern, please feel free to contact us anytime to provide us more details. Thank you.