If you are expected to write a case study on the 7 functions of an HRD Manager, I would suggest creating a fictional company that has fewer than 50 employees.  Identify some roles in that company such president/CEO, secretary, product or sales team, small shipping/receiving group, a finance or accounting person or team, etc.  Put your imagination to work and you can create a scenario that identifies the many functions of this position.

Each person in the company would have some relationship to the HRD Function.  Your analysis of those relationships would help you write the case study of what the HRD Manager does for the organization.

HR is concerned with

• getting the right employees into the right jobs within an organization (recruitment and hiring),
• motivating them to perform (interactions with managers and employees, benefits that add motivation, policies that are fair and are perceived as fair by employees),
• keeping the organization legal (training managers and supervisors in legal employment and supervision issues), and
• retaining good employees (training, policies, etc.)

There are a host of other issues related to these bullet points, but you get the idea.  So think about how the HRD Manager would have to interact with people in the organization to accomplish all this.

Your case study could follow the HRD Manager in a "typical" week.  You could include discussion of meetings, planning, correspondence, interviews, and basic interactions with employees at various levels of the organization.  These could be written to provide a glimpse into the ongoing functions of the position and reference future activities that demonstrate the remaining functions of the position.