How to use Nivo Slider on woocommerce

Can someone explain in simple terms how I use the Nivo Slider on the woocommerce pluggin?

It tells me to:

Place this: <?php if (function_exists(‘nivoslider4wp_show’)) { nivoslider4wp_show(); } ?> in your templates

but how to I access my templates and add it?

I’m a complete noob at this so I need to know in noob terms.

Thanks

Dan