How to add indexers in c#

    public class Employee
    {
        public Employee(string name, int id)
        {
            this.Name = name;
            int ID = id;

        }
        public string Name { get; set; }
        public  int ID { get; set; }
    }
    public class Company
    {
        private List<Employee> listWithEmployees;
        public Company()
        {
            this.listWithEmployees = new List<Employee>();
        }

        public void AddEmployee(Employee employee)
        {
            this.listWithEmployees.Add(employee);
        }

        public string this[int employeeID]
        {
            get
            {
                return listWithEmployees.FirstOrDefault(e => e.ID == employeeID).Name;
            }
            set
            {
                listWithEmployees.FirstOrDefault(e => e.ID == employeeID).Name = value;
            }
        }
    }