Canada / US plan

Last December I signed up for the Canada/US plan.  I want to know how to use my phone in the USA?  Do I need to use Airplane mode, or some such other thing?  Or is it just like using it in another area of Canada and no action is needed?  Texts  - pictures - calls to Canada from the USA - calls to another cell phone - my wife - with the same plan while in the states.  Local calls in the states while in the states.  

Any help is appreciated.

Boo1