How do I use Blogger API v3.0

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C#5.0

API

private string HTTPPost(string url, string postparams)
{
string responseString = "";

// performs the desired http post request for the url and parameters
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
// request.CookieContainer = Cookie; // explicitely use the cookiecontainer to save the session

string postData = postparams;
byte[] data = Encoding.UTF8.GetBytes(postData);

request.Method = "POST";
request.ContentType = "multipart/form-data";
request.ContentLength = data.Length;

using (var stream = request.GetRequestStream())
{
stream.Write(data, 0, data.Length);
}


var response = (HttpWebResponse)request.GetResponse();


responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();

return responseString;

}

public class AccessToken
{
[JsonProperty(PropertyName = "access_token")]
public string access_token { get; set; }
}

private void Form1_Click(object sender, EventArgs e)
{
string Code = "code=" + "4/IivfhM7o5fd4fM6rLp6fHs1nhm5AeCIkO8iL_JcH9jg" + "&";
string ID = "client_id=29150183913-us8ansgqd27i0prnnch0576a93ahdi9f.apps.googleusercontent.com&";
string uri = "redirect_uri=urn:ietf:wg:oauth:2.0:oob&";
string grant = "grant_type=authorization_code&";
string secret = "client_secret=rsPLgZ-fD7_qHOTyqObxGE5O";

string Code2 = HTTPPost("https://www.googleapis.com/oauth2/v3/token", Code + ID + uri + grant + secret);

AccessToken JsonAccToken = (AccessToken)JsonConvert.DeserializeObject(Code2, typeof(AccessToken));
string StrAccToken = JsonAccToken.access_token;


try
{
JSONPublish("7962677485521194204", "Testpost", "This is a Test.", StrAccToken);
}
catch (Exception)
{

throw;
}
}

private void JSONPublish(string sid, string stitle, string scontent, string token)
{
var http = (HttpWebRequest)WebRequest.Create(new Uri("https://www.googleapis.com/blogger/v3/blogs/" + sid + "/posts/"));
http.Accept = "application/json";
http.ContentType = "application/json";
http.Method = "POST";
http.Headers.Add("Authorization", "Bearer " + token);

var vm = new { kind = "blogger#post", blog = new { id = sid }, title = stitle, content = scontent };
var dataString = JsonConvert.SerializeObject(vm);
string parsedContent = dataString;

Byte[] bytes = Encoding.UTF8.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);
}







here is the Code I face Error at this line var response = (HttpWebResponse)request.GetResponse(); I face error of 400 bad request
I need Help how can I fix this..
And I don`t know what type of value given to him

string uri = "redirect_uri=urn:ietf:wg:oauth:2.0:oob&";
         string grant = "grant_type=authorization_code&";