Employee.cs

namespace ProjectCompany
{
    public class Employee
    {
        private string firstName;
        private string secondName;
        private Company company;
        private Employee supervisor;

        public Employee (string firstName, string secondName, Company company, Employee supervisor)
        {
            this.firstName = firstName;
            this.secondName = secondName;
            this.company = company;
            this.supervisor = supervisor;
        }
        
        private string fullName
        {
            get
            {
                return string.Format("{0} {1}", firstName, secondName);
            }
        }
        
        public override string ToString() 
        {
            return string.Format("Supervisor of {0} is {1}", fullName, supervisor != null ? supervisor.fullName : "N/A");
        }
    }
}

Program.cs

namespace ProjectCompany
{
  public static class Program
  {
    private static readonly List<Employee> employees = new List<Employee>();
    
    public static void Main()
    {
      // Add an employee...
      AddEmployee();
      
      PrintEmployees();
    }
    
    private static void AddEmployee()
    {
      string firstName = string.Empty;
      string secondName = string.Empty;
      
      Console.Write("First name: ");
      firstName = Console.ReadLine();
      
      Console.Write("Second name: ");
      secondName = Console.ReadLine();
      
      // TODO: Find supervisor and company...
      Company company = null;
      Employee supervisor = null;
      
      var employee = new Employee(firstName, secondName, company, supervisor);
      
      employees.Add(employee);
    }
    
    private static void PrintEmployees()
    {
      foreach (var employee in employees)
      {
        Console.WriteLine(employee)
      }
    }
  }
}