What happens next?

How to use headphones on an iphone 7
Locate your iphone's lightning port.
While the 3.5 millimeter headphone jack is gone, the traditional charging port--also known as the lighting port--is still at the bottom of your phone. You'll plug your lightning headphones cable into this slot.
Plug your headphones into the lightning port. These should fit into the lightning port the same way your iphone 5 or 6 charger does.