Open Integrations in your dashboard and pick the integration you want to use. The embed snippet is at the top of the page.
Paste it just before the closing body tag of your site, on every page you want the bubble to appear. If your site is built from one shared layout or template, pasting it there covers the whole site at once.
The script is cached for five minutes, so a first paste shows up almost immediately. Changes you make to the widget's colours and greeting go live on the next page load without touching the snippet again.
If the bubble does not appear, check that your subscription is active and that the snippet was not stripped by a security plugin or a content filter.