How to get the correct filepath in webform

I'm working in the web.config, in the appSettings.  my FileUploadServiceUrl's value is: "http://localhost/PWControlServices/FileUpload.ashx?filename{0}&append={1}&FolderPath={2}" 
The FileUploadBasePath's value is: "\\myfiler\myadmin\my_Test"
Question is, what should my FileUploadBaseUrl value be?  http://localhost:33020/my_Test ???  I get an error file not found here.