Steam avatar changer

void Main()
{
    string URL = "http://steamcommunity.com/actions/FileUploader";
    string boundary = "-----" + DateTime.Now.Ticks.ToString("x");
    HttpWebRequest webRequest = (HttpWebRequest)System.Net.HttpWebRequest.Create(URL);

    webRequest.Method = "POST";
    webRequest.ContentType = "multipart/form-data; boundary=" + boundary;
    webRequest.CookieContainer = new CookieContainer();
    webRequest.CookieContainer.Add(new Cookie("steamLogin", "<Your auth cookie goes here>", "/", "steamcommunity.com"));

    string FilePath = @"C:\Users\HLSDK\Desktop\draw\wat_novi.png";

    NameValueCollection formData = new NameValueCollection();

    formData.Clear();
    formData["MAX_FILE_SIZE"] = "204800";
    formData["type"] = "player_avatar_image";
    formData["sId"] = "<64 bit steamid>";
    formData["doSub"] = "0";

    Stream postDataStream = GetPostStream(FilePath, formData, boundary);

    webRequest.ContentLength = postDataStream.Length;
    Stream reqStream = webRequest.GetRequestStream();

    postDataStream.Position = 0;

    byte[] buffer = new byte[1024];
    int bytesRead = 0;

    while ((bytesRead = postDataStream.Read(buffer, 0, buffer.Length)) != 0)
    {
        reqStream.Write(buffer, 0, bytesRead);
    }

    postDataStream.Close();
    reqStream.Close();

    StreamReader sr = new StreamReader(webRequest.GetResponse().GetResponseStream());
    string Result = sr.ReadToEnd();
    Result.Dump();
}

private static Stream GetPostStream(string filePath, NameValueCollection formData, string boundary)
{
    Stream postDataStream = new System.IO.MemoryStream();

    //adding form data
    string formDataHeaderTemplate = Environment.NewLine + "--" + boundary + Environment.NewLine +
        "Content-Disposition: form-data; name=\"{0}\";" + Environment.NewLine + Environment .NewLine + "{1}";

    //adding file data
    FileInfo fileInfo = new FileInfo(filePath);

    string fileHeaderTemplate = Environment.NewLine + "--" + boundary + Environment.NewLine +
        "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"" +
        Environment.NewLine + "Content-Type: image/png" + Environment.NewLine + Environment.NewLine;

    byte[] fileHeaderBytes = System.Text.Encoding.UTF8.GetBytes(string.Format(fileHeaderTemplate,
        "avatar", fileInfo.Name));

    postDataStream.Write(fileHeaderBytes, 0, fileHeaderBytes.Length);

    FileStream fileStream = fileInfo.OpenRead();

    byte[] buffer = new byte[1024];

    int bytesRead = 0;

    while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
    {
        postDataStream.Write(buffer, 0, bytesRead);
    }

    foreach (string key in formData.Keys)
    {
        byte[] formItemBytes = System.Text.Encoding.UTF8.GetBytes(string.Format(formDataHeaderTemplate,
        key, formData[key]));
        postDataStream.Write(formItemBytes, 0, formItemBytes.Length);
    }

    fileStream.Close();

    byte[] endBoundaryBytes = System.Text.Encoding.UTF8.GetBytes("--" + boundary + "--");
    postDataStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);

    return postDataStream;
}

// Define other methods and classes here