using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        Dictionary<string, object> myDict = new Dictionary<string, object>();

        myDict.Add("task", new Dictionary<string, object>());

        Dictionary<string, object> innerDict = (myDict["task"] as Dictionary<string, object>);

        innerDict.Add("taskState", "Running");

        innerDict.Add("taskStatus", "Ok");

        innerDict.Add("completedSteps", 1);

        innerDict.Add("taskProgress", new List<dynamic>());

        List<dynamic> taskProgress = (innerDict["taskProgress"] as List<dynamic>);

        taskProgress.Add(new { message = "test message", timeStamp = DateTime.Now });

        string json = JsonConvert.SerializeObject(myDict, Formatting.Indented);

        Console.WriteLine(json);

        Console.ReadLine();

    }

}