The two lines
<script src="https://hazelsong.com/widget/YOUR-SLUG.js?template=wall" async></script>
<div id="hazelsong-wall"></div>Your own slug, and the tag ready to copy, are in your dashboard. Choosing a different one of the 23 layouts means adding ?template=marquee to the src — never touching the page again. Adding &tag=onboarding shows only the testimonials carrying that label, so one page can hold the words about one thing you do; the label is one you added in your dashboard, and only the matching ones are sent to the page. A label nothing carries shows an empty wall rather than quietly falling back to everything.
Where it goes
14 builders that run a script tag.
And the ones that cannot
These 3 will not run a third-party script, by their own design. That is worth knowing before you sign up for anything, so it is on the index rather than in a support article.
Your testimonials, on your page, this afternoon
Collect one, publish it, paste two lines. There is no build step anywhere in this.