Includin source link

Hi everyone.
I need alitle help to fix this issue.
I have aform, wich i will replace on every page in my website, a have a Hidden input field, i want that the value of that field be the link wich guest has submitted the form from.
like a Telling a friend script.

altso something like this.

<?php echo $QUERY_STRING ?>

can it be done?
and how plz?!

thanks.