How to develop a method to get all the employees within specific organization by accessing web service?

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C#

I have two intranet web services in my company to retrieve the employee information and organization information as well.These web services will be utilized by the developers for developing intranet web-based applications for the company.
I am trying to develop a simple console application that will retrieve the following information:

1. Get the employee information by entering the username
2. Get the organization (such as department, division...) information by the sap code
3. Find all the employees under the organization

**I already developed the first two items by creating two classes for each item, and now I am struggling with the third item due to the fact that I am a beginner in C#. I don't know how to come up with a list of all employees within the organization. I really appreciate any help that will show me how to implement this part. What I think I should do is develop a method where I can pass the sapCode of the organization to get the list of its employees. So Could you please help me in developing this third item?**