How do I obtain an authorize code from OneDrive with LiveSDK

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cloud

C#5.0

client-side

OneDrive

Hello together,
I have got a question about OneDrive's LiveSDK.
I want to find a way how to sign in a user without using login informations (e-mail and password), and nothing to accept, because my service should automatically sign in the user in the background, so that he can't see anything. So the only way I know to create a session is to obtain an authorize code, and in the documentations it says that when requesting an authorize code the user has to sign in and a window will pop up. But this is exactly what I not want to have.
So I hope you may be able to help me and hopefully have a solution for my problem.
Here the code i used to get an authorize code, there should be an URL as a result with the authorize code, but i get a huge html code.

Uri url = new Uri("https://login.live.com/oauth20_authorize.srf");

            using (var wb = new WebClient())
            {
                var data = new NameValueCollection();
                data["client_id"] = "client_id";
                data["scope"] = "wl.signin%20wl.basic%20wl.offline_access";
                data["response_type"] = "token";
                data["redirect_uri"] = "redirect_uri";       //bekomme ich zurück? als response

                var response = wb.UploadValues(url, "GET", data);

                
                string a = System.Text.Encoding.UTF8.GetString(response);