flickrrss styling problem

Ok I installed flickrrss and got it working now I want to style it. I know from a previous post that am supposed to wrap the widget in a div like so.

<div id=”flickr”>
<?php get_flickrRSS(); ?>
</div>

however the problem I run into is that i have no clue where this
<?php get_flickrRSS(); ?> is located. According to the instructions you install the flickrrss in your plugs ins and place <?php get_flickrRSS(); ?> somewhere in your code. I did not do the second step however it works on my blog. All i did was activate the widget in the dashboard. All i want to know is be able to control the size of the thumbnails!! please help I have spent all day trying to figure this out. Thanks