Sounds like this is an issue with how you have set permissions. You may need to simply allow an anonymous user/general public to open the page for which you are getting the "forbidden" message. Check your permissions perhaps? Doesn't sound like a fault with WinSCP.

When I want to use forms and I make a new dirctory cgi-bin, when I go to browser it becomes an error, forbiden , what is the problem.
thanks.