Scripting events with php

My problem is that I want to use events in my forms but I do not know how to use php as a script for an event. Say I wanted to do something as simple as (within a form): <input type="button" value="Test" onclick= <?php print 'testing, testin 123';?>> Essentially, when a click this button in a form it prints out testing. A more sophicisticated problem i had, was i wanted to print out multiple repeats of a form based upon user input. I have a user database, where during the initial profile setup, they can specificy potentially large amount of interests that they have. I would like for them to be able to say: I have 5 interests, click a button then 5 textboxes popup. dmp