functions.php not in editor

[WhatKidsToys.com]

Hi There

I'm using church theme 4.0 and have recently upgraded to the latest wordpress version 3.2.1 for my site http://northernbeachesfloorball.com.au

I had used featured content gallery and have updated with dynamic content gallery. I followed all the tutorials and believe have installed all properly. The issue seems to be that the version of dynamic content gallery requires my theme to support WP Post Thumbnails feature. After reading a few of the DCG trouble shooting posts i believe I have to include the following code to functions.php
add_theme_support('post-thumbnails');
Problem is that I don't have functions.php in my church theme editor?! Is there another place I should place the above code?
Thanks for your help