Let's add a new field by clicking
Expand the Type dropdown and select "text".
Notice the Testimonial Title and Testimonial Content options are disabled, but Featured Image is available because we removed "Photo" before.
Only one new field can be added at a time so thebutton is disabled until this field is complete.
Enter "City" in the label property.
Move to the next property by Tab or click and the Name and Title will update automagically.
Change the Name if you want. Or erase the Name and it will be generated again.
In the Placeholder property, enter "what city are you in?"
We're done with this field so click