Where to insert an (existing) JavaScript Snippet that makes Google displaying my ProvenExpert rating stars in its organic search?

Hello from Berlin.

I’m not familiar with coding, first. From a customer review service I got a code snippet, what makes Google to show my rating stars in the organic search. It must be inserted into the HTML body, they sayd. But where can I edit the HTML body of a WiX page? Thank you so much…

<div class="pe-richsnippets"></div>
<script type="text/javascript" src="https://www.provenexpert.com/widget/richsnippet.js?u=xxxxxxxxxxxx" async></script>