How to edit Billing Information on Order Form?

Hello World. I have an Order Form for a Product. In the Billing Information section of the Order Form is a field for State. My customers are Canadian. We have Provinces, not States.
I want to customize the Order Form to change the label of the State field to Province.
Also, I can’t seem to access the HTML tab from the Order Form area.
How do I do this? Is there a developer out there who can do this?