If you know exactly where the file should be stored and if is a constant path, then you can save in the config file or DB. Then you can read the path and append the filename with it and finally save.
in config: <add key="UploadPath" value="\\fsvcsdev5536\App\Files"/>
in code:
string folderPath = ConfigurationManager.AppSettings["UploadPath"].ToString();
string fileDest = folderPath + "\\" + fileName.trim();
this.flUpld.SaveAs(fileDest);