To add content to or update content on a Landing Page, navigate to the page and select the Layout tab to access the Layout view. You will then be shown an outline of the existing page with buttons at the top to Save, Discard, or Revert your changes.
Be aware that most changes are retained in a temporary buffer that persists even if you navigate off to another page of the website. Changes stored in that buffer are not reflected on the published page until you select the Save layout button on the Layout view. If you want to throw out your latest changes, select the Discard changes button to take your Layout view back to your last published version.