It sounds like you are referring to the Tracking Tools & Analytics. Here you can add custom code snippets to your site for analytic tools.
Code snippets are not added to your site as an iFrame, and are invisible to your site visitors. If you wish to embed visible code on your site, you should use the HTML app (We will implement this very soon).
How to find the Tracking Tools & Analytics:
Go to Settings in your site’s dashboard.
Click the Tracking & Analytics tab under Advanced Settings.