POSTing JSON to URL via WebClient in C#

I have some JavaScript code that I need to convert to C#. My JavaScript code POSTs some JSON to a web service that's been created. This JavaScript code works fine and looks like the following:

var vm = { k: "1", a: "2", c: "3", v: "4" };
$.ajax({
  url: "http://www.mysite.com/1.0/service/action",
  type: "POST",
  data: JSON.stringify(vm),
  contentType: "application/json;charset=utf-8",
  success: action_Succeeded,
  error: action_Failed
});

function action_Succeeded(r) {
  console.log(r);
}

function log_Failed(r1, r2, r3) {
  alert("fail");
}

I'm trying to figure out how to convert this to C#. My app is using .NET 2.0. From what I can tell, I need to do something like the following:

using (WebClient client = new WebClient())
{
  string json = "?";
  client.UploadString("http://www.mysite.com/1.0/service/action", json);
}

I'm a little stuck at this point. I'm not sure what json should look like. I'm not sure if I need to set the content type. If I do, I'm not sure how to do that. I also saw UploadData. So, I'm not sure if I'm even using the right method. In a sense, the serialization of my data is my problem.

Can someone tell me what I'm missing here?

Thank you!

The question is already answered but I think I've found the solution that is simpler and more relevant to the question title, here it is:

var cli = new WebClient();
cli.Headers[HttpRequestHeader.ContentType] = "application/json";
string response = cli.UploadString("http://some/address", "{some:\"json data\"}");

PS: In the most of .net implementations, but not in all WebClient is IDisposable, so of cource it is better to do 'using' or 'Dispose' on it. However in this particular case it is not really necessary.

The following example demonstrates how to POST a JSON via WebClient.UploadString Method:

var vm = new { k = "1", a = "2", c = "3", v=  "4" };
using (var client = new WebClient())
{
   var dataString = JsonConvert.SerializeObject(vm);
   client.Headers.Add(HttpRequestHeader.ContentType, "application/json");
   client.UploadString(new Uri("http://www.contoso.com/1.0/service/action"), "POST", dataString);
}

> Prerequisites: Json.NET library

You need a json serializer to parse your content, probably you already have it, for your initial question on how to make a request, this might be an idea:

var baseAddress = "http://www.example.com/1.0/service/action";

var http = (HttpWebRequest)WebRequest.Create(new Uri(baseAddress));
http.Accept = "application/json";
http.ContentType = "application/json";
http.Method = "POST";

string parsedContent = <<PUT HERE YOUR JSON PARSED CONTENT>>;
ASCIIEncoding encoding = new ASCIIEncoding();
Byte[] bytes = encoding.GetBytes(parsedContent);

Stream newStream = http.GetRequestStream();
newStream.Write(bytes, 0, bytes.Length);
newStream.Close();

var response = http.GetResponse();
     
var stream = response.GetResponseStream();
var sr = new StreamReader(stream);
var content = sr.ReadToEnd();

hope it helps,