If they answer no I want a box to open to have them explain why?
There is if you have a PROFESSIONAL or ENTERPRISE level account.
Open the question with EDIT and then edit the NO option. Change the SPECIAL SETTINGS to “OTHER – WRITE IN”.
You could also just use regular question logic for this, which is explained in sg’s documentation section. Here’s the link to it: http://help.surveygizmo.com/help/article/link/setup-question-logic