How do I change the text for the prereq element to "Before you begin"

Hi,

I am creating structured docs in DITA (eventually to be published online using RoboHelp), and I want to make, for example, the following changes:

- Change prereq element label text to "Before you begin"

- Add a label to the context element that says "About this topic"

- Change the steps element label text to "Procedure"

- Remove the "Additional Information" label for the step info element.

You get the idea. Can someone at least point me in the right direction? Will I need to create an EDD? Modify the existing one? Something else altogether? Can you point me to the chapter in the Help that covers how to do this?

Thanks!!