using System;
using System.IO;
using System.Net;
using System.Web.Script.Serialization;

public class Test
{
	public class YourClass
	{
		public string someValue= "";
		public string otherValue = "";
		public string differentValue = "";

	}

 public static string GetKey()
 {
     var yc = new YourClass();
     string requestBody = "{\"someValue\": \"this is some data\",\"otherValue\": \"other data appears here\",\"differentValue\": \"different data \"}";
     string endpoint = "https://someendpoint/api";

     // set up the Http request
     var yourHttpRequest = (HttpWebRequest)WebRequest.Create(endpoint);
     yourHttpRequest.ContentType = "application/json";
     yourHttpRequest.Method = "POST";

     // write the body of the http request
     using (var sw = new StreamWriter(yourHttpRequest.GetRequestStream()))
     {
     	sw.Write(requestBody);
     	sw.Flush();
     	sw.Close();
     }

     // get and parse the response
     using (var yourHttpResponse = (HttpWebResponse)yourHttpRequest.GetResponse()) {

       // parse the json returned
    	using (var reader = new StreamReader(yourHttpResponse.GetResponseStream())){
    		JavaScriptSerializer js = new JavaScriptSerializer();
    		var objText = reader.ReadToEnd();
    		yc = js.Deserialize<YourClass>(objText);

    	}

    }

     return yc.someValue;
 }