This bugs me for the last couple of days - after drilling into Send Notes from Notecard to Notehub, my in-browser terminal page is long over-written - and my solution at the moment is to navigate to Home and from there find my way to (browser) page that hopefully contains the currently active in-browser terminal.
Suggestion: it would be nice if one could create a new browser page with the terminal - similarly to the way one can extract the Chrome DevTools window outside of the browser window running the web app.
If you open the Notecard Playground in a separate tab, this will allow you to access any guides/tutorials/docs you want while still having access to your Notecard session.