You'll need a Website, a Server, and a Smooch app.
On your server expose a POST /events endpoint. It should accept an event type, and a Smooch user ID as JSON data. When this endpoint is called the server should call the Smooch REST API with an appropriate message for the user. Something like this:
curl https://api.smooch.io/v1/appusers/{{userId}}/messages \
-X POST \