[c#] Setting a WebRequest's body data

I'm creating a web request in ASP.NET and I need to add a bunch of data to the body. How do I do that?

var request = HttpWebRequest.Create(targetURL);
request.Method = "PUT";
response = (HttpWebResponse)request.GetResponse();

Update

See my other SO answer.

Original

var request = (HttpWebRequest)WebRequest.Create("https://example.com/endpoint");

string stringData = ""; // place body here
var data = Encoding.Default.GetBytes(stringData); // note: choose appropriate encoding

request.Method = "PUT";
request.ContentType = ""; // place MIME type here
request.ContentLength = data.Length;

var newStream = request.GetRequestStream(); // get a ref to the request body so it can be modified
newStream.Write(data, 0, data.Length);
newStream.Close();

The answers in this topic are all great. However i'd like to propose another one. Most likely you have been given an api and want that into your c# project. Using Postman, you can setup and test the api call there and once it runs properly, you can simply click 'Code' and the request that you have been working on, is written to a c# snippet. like this:

var client = new RestClient("https://api.XXXXX.nl/oauth/token");
client.Timeout = -1;
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Basic   N2I1YTM4************************************jI0YzJhNDg=");
request.AddHeader("Content-Type", "application/x-www-form-urlencoded");
request.AddHeader("Content-Type", "application/x-www-form-urlencoded");
request.AddParameter("grant_type", "password");
request.AddParameter("username", "[email protected]");
request.AddParameter("password", "XXXXXXXXXXXXX");
IRestResponse response = client.Execute(request);
Console.WriteLine(response.Content);

The code above depends on the nuget package RestSharp, which you can easily install.