using System;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        var jToken = JToken.Parse("{ \"root\": { \"nested\": { \"value1\": \"something\" } } }");

        var selectedToken = jToken.SelectToken("$.root.nested");

        if (selectedToken != null)

        {

            selectedToken["newValue1"] = new JValue("something new");

            selectedToken["nested2"] = JObject.FromObject(new { foo = "bar" });

        }

        Console.WriteLine(jToken.ToString());

    }

}