如果获取上传文件的进度？

如果获取上传文件的进度？
try
            {
                FileInfo file = new FileInfo(fileNamePath);
                
                string fileNameExt = file.Extension;
                if (CheckVideoFileType(fileNameExt))
                {
                    string fileName = GetNewFileName() + fileNameExt;
                    if (toFilePath.EndsWith("/") == false) toFilePath = toFilePath + "/";
                    
                    string serverFileName = toFilePath + fileName;
                                        
                    string toFileFullPath = HttpContext.Current.Server.MapPath(toFilePath);                    
                    if (!Directory.Exists(toFileFullPath))
                    {
                        Directory.CreateDirectory(toFileFullPath);
                    }                                    
                    string toFile = toFileFullPath + fileName;                          
                    WebClient myWebClient = new WebClient();
                    
                    myWebClient.Credentials = CredentialCache.DefaultCredentials;
                                              
                    FileStream fs = new FileStream(fileNamePath, FileMode.Open, FileAccess.Read);
                          
                    BinaryReader r = new BinaryReader(fs);
     
                    byte[] postArray = r.ReadBytes((int)fs.Length);
                    Stream postStream = myWebClient.OpenWrite(toFile, "PUT");
if (postStream.CanWrite)
                    {}该怎么写呢？