C# How can I send a file in an api using httpclient in net core?

Code
[Route("[controller]/pu/SendArchive")]

        [SwaggerOperation("SendArchive")]

        public async Task SendArchive([FromBody] Archive archive, string request) 

        {

            var username = "";

            var password = "";

            var name = "Job";



            var authInfo = username + ":" + password;

            var encoded = Convert.ToBase64String(Encoding.Default.GetBytes(authInfo));

            var requestURL = "http://cobpm01p.mar.net/rest/bp/wle/v1/process/" + request +

                                         "?action=addDocument&name=" + name + "&docType=file&data=data";



            var postParameters = new Dictionary<string, object>();

            postParameters.Add("data", new FormUpload.FileParameter(archive.content, archive.fileName, archive.mimeType));

            //string userAgent = null;

            var webResponse = FormUpload.MultipartFormPost(Uri.EscapeUriString(requestURL), userAgent,

                postParameters,

                "Authorization", "Basic " + encoded);

            // Process response  

            var responseReader = new StreamReader(webResponse.GetResponseStream());

            var returnResponseText = responseReader.ReadToEnd();

            webResponse.Close();

            var results = JsonConvert.DeserializeObject<dynamic>(returnResponseText);

            if (results.status == "200") {

            }

                

        }