questions4wp on "Contact Form 7 jQuery hooks"

After a ton of research, I'm having a heck of a time finding any guide to adding a simple jQuery hook to a change in a Contact Form 7 form.

What I'm looking for is simple (I think) - an onChange event for a dropdown that yields a popup saying "dropdown has changed". I've seen a number of posts with no responses, as well as people posting vague comments like "just use jQuery" - does anyone have any practical advice on where to put what in order to achieve something simple like this?

I have attempted the following - I made labeled the dropdown box with the ID "firstDropDown", and I added this to my header.php:

<script type="text/javascript">
	jQuery(function($){
		$("#firstDropDown").change(
			function() {alert("Dropdown has changed.");}
		);
	};
</script>

But alas, no luck.