Your first stop should be the HTML editor. While editing an essay or page, click the brackets button at bottom right. An inline text editor will appear displaying the HTML markup of the essay/page you're currently writing. You may use this to adjust the automatic HTML markup the rich text editor is applying, or insert your own code.
There is one important gotcha however — all code entered into the HTML editor flows through the rich text editor, which is configured to automatically remove
<script> markup that may pose a security risk. If you run into this, insert the code instead, as we'll explain next.
A sheet will appear where you may write or paste the code you want included in the essay/page.
You may then click on the bar to make edits thereafter, if needed.