Your question is actually more Apache than Perl, but I've got a second at the moment. The probabilities are:
- You haven't restarted your apache.
- Your file permisions (you didn't specify your OS).
- You haven't got your permissions right in your apache .conf file for that location.
Your apache error log holds the keys to your particular problem
In actuality this site would be best for getting your questions answered after you've got your simple.cgi script working. The apache mailing list would probably be of better help at this point.