How do I make a master detail template into a catalog?

The app: I need to make an iPad app for cashiers at a small school uniform business to ring up customers.  Using the master detail view template, The schools are listed in the master view.  Depending on which school is selected, the available uniforms in detail view should change to the one's for that specific school.  Also, these uniforms should have a cost associated with them and a way to select quantity so they can be totaled up after being added to the cart.

Quick description of what I have so far:  So far, I have it so the app has different school in the master view.  I am having a hard time making it populate with different uniforms when one of the schools is selected.