You're confused about the relationship of XSLT to HTML. Your XSLT stylesheet generates the HTML page and then finishes execution. Then the browser displays the generated page. By the time the user enters values in the textbox, XSLT has done its job and gone home for tea.
You can fire off another transformation from Javascript in response to user input, but it's not clear that this is the right solution to your problem.
Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference