[Plugin: Nextend Smart Slider 2 Full] Showing plugin on homepage only

I’ve upgraded my slider 2 plugin for the nextend slider. I have the slider currently on a temporary page called portfolio, but I want it on my main page instead.

The code I need to paste in is:

<?php
echo do_shortcode('[smartslider2 slider="1"]');
?>

But where do I put it so it only shows up on my homepage? Index.php? (I am using a coller child theme.)