I receive no data in this variable "$ENV{'QUERY_STRING'}"

In the form element of the html file, what is the value of the method attribute? It should be either "get" or "post". If it's "get", your form data should come in via $ENV{QUERY_STRING}, but if it's "post", then your form data should come in via standard input and will be formatted somewhat differently. I think CGI specifies how this works, so it should be largely the same in IIS as it is in Apache, although I haven't worked much with IIS so there could be minor differences I don't know about.