As title said:
using System;
using System.Collections;
using System.Linq;

namespace IEnumarable
{
  class Program
  {
    static void Main(string[] args)
    {
      MyIEnumerable myIEnumerable = new MyIEnumerable();

      foreach (string test in myIEnumerable.Cast<string>().ToList())
      {
        Console.WriteLine(test);
      }
    }

    class MyIEnumerable : IEnumerable
    {
      private string _names = "stanko, milosev, elizabeta, lazarevic";

      public IEnumerator GetEnumerator()
      {
        string[] aryNames = _names.Split();

        foreach (string name in aryNames)
        {
          yield return name;
        }
      }
    }
  }
}
POI:
myIEnumerable.Cast().ToList()