hi, WBS means, work breakdown structure....this will provide you direction to start with. if you are still not finding direction, try to talk with the department head with prior appointment.
Prepare questionnairs, it will help you to understand the business process. Dont be in hurry to understand everything, go gradually, but understand processes right from micro level.
Basic flow for use case can be identified from Business Requirement Documents or Functional Requirement Documents as these use cases are prepared on the basis of these requirement.
Actually use case can be tracked / identified through business requirement document or functional requirement documents. Because these use cases are prepared on the basis of each requirements or process mentioned in the documents.
