finding c# ways to send http requests

I am trying to deve开发者_开发知识库lop a Microsoft excel plugin to send excel sheet data to a web application. It will require the plugin to prompt username and password and then send login http request to the web application to get a session . Then it will upload data to the web application . What .net things should I use ?

Post Method Sample for send username and password. for uploading file just search "File Upload C#" in google.com or bing.com or try C#'s WebClient.UploadFile, Code Project

// Create a request using a URL that can receive a post. 
WebRequest request = WebRequest.Create("http://example.com");
// Set the Method property of the request to POST.
request.Method = "POST";
// Create POST data and convert it to a byte array.
string postData = "username=user&passsword=pass";
byte[] byteArray = Encoding.UTF8.GetBytes (postData);
// Set the ContentType property of the WebRequest.
request.ContentType = "application/x-www-form-urlencoded";
// Set the ContentLength property of the WebRequest.
request.ContentLength = byteArray.Length;
// Get the request stream.
Stream dataStream = request.GetRequestStream ();
// Write the data to the request stream.
dataStream.Write (byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close ();
// Get the response.
WebResponse response = request.GetResponse ();
// Display the status.
Console.WriteLine (((HttpWebResponse)response).StatusDescription);
// Get the stream containing content returned by the server.
dataStream = response.GetResponseStream ();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader (dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd ();
// Display the content.
Console.WriteLine (responseFromServer);
// Clean up the streams.
reader.Close ();
dataStream.Close ();
response.Close();                                                                                         

For HTTP communication in .NET, try System.Net.WebClient or System.Net.HttpWebRequest.