To modify the data values passed into the test, edit the Endless-Aisle-Test/tests/common/globals.js file. Update this file with associate, catalog and customer data for your site. A good place to start with is to update the associate login_id and login_password for your site.
To create new tests, you can use the eaa-test-template.js file as a starting point.
In the common/features directory are helper files by feature, to let you easily use these methods in your tests and reduce duplicity of code.
For more details, see: The Guide for Using Appium.