Collections Data Structure C#

using System;
using System.Collections;
public class Employee
{
    public Employee(string fName, string lName)
    {
        this.firstName = fName;
        this.lastName = lName;
    }
    public string firstName;
    public string lastName;
}
public class EmployeeCollection : IEnumerable
{
    private Employee[] _people;
    public EmployeeCollection(Employee[] pArray)
    {
        _people = new Employee[pArray.Length];
        for (int i = 0; i < pArray.Length; i++)
        {
            _people[i] = pArray[i];
        }
    }
    IEnumerator IEnumerable.GetEnumerator()
    {
       return (IEnumerator) GetEnumerator();
    }
    public EmployeeCollectionEnum GetEnumerator()
    {
        return new EmployeeCollectionEnum(_people);
    }
}
public class EmployeeCollectionEnum : IEnumerator
{
    public Employee[] _people;
    int position = -1;
    public EmployeeCollectionEnum(Employee[] list)
    {
        _people = list;
    }
    public bool MoveNext()
    {
        position++;
        return (position < _people.Length);
    }
    public void Reset()
    {
        position = -1;
    }
    object IEnumerator.Current
    {
        get
        {
            return Current;
        }
    }
    public Employee Current
    {
        get
        {
            try
            {
                return _people[position];
            }
            catch (IndexOutOfRangeException)
            {
                throw new InvalidOperationException();
            }
        }
    }
}
class App
{
    static void Main()
    {
        Employee[] peopleArray = new Employee[3]
        {
            new Employee("A", "D"),
            new Employee("B", "E"),
            new Employee("C", "F"),
        };
        EmployeeCollection peopleList = new EmployeeCollection(peopleArray);
        foreach (Employee p in peopleList)
            Console.WriteLine(p.firstName + " " + p.lastName);
    }
}