Peter.
The markup is added to content (text) on your website already.
For example, if you have your address and phone number placed in your footer or sidebar, you would add the markup to them.
So naturally where ever you fell your content should sit within the aesthetics of your website, you just add the schema markup around that content.
If for example you have your address in the footer on every page, yes add the markup to every page. Marking up as much content as possible can help the search engines.
Or if you have an events page, with several events on that page, you would add the markup to each event.
Have a look here ... if you have not already http://schema.org/LocalBusiness
There are lots of properties you can use ...
Hope that helps
Regards
John