Teachable requires Chatwing code to begin with HTTPS which is possible by using Chatwing SSL features available under "General Options" after Upgrading your Chatwing to advanced mode.
In the Chatwing Dashboard, customize your Chatwing chatbox and click "Use Chatbox" and under "Embedded Options" select the size of your chatbox and copy the iFrame HTML code
In the Teachable Dashboard www.Teachable.com open a course and create a new text block. Then click the <> button on the top left of the text editor. That will place the editor into raw HTML mode. You can then add your Chatwing embed code (from Step 2 above) here inside Teachable.
You can then Preview the course with the chat live