Adobe PageMill has two modes: Preview and Edit. The current mode is indicated by the button in the upper right corner of the window.
The globe icon at the upper right of the page indicates that you are in Preview mode. Preview mode simulates how the page looks and behaves when viewed in a Web browser.
The pen-and-paper icon indicates you are in Edit mode. In Edit mode you can create or modify the content and design of the page-enter and edit text, manipulate images, create links, and so on.
Click the globe to change to Edit mode.
In the preferences dialog box, you can specify whether you want existing pages to be opened in the preview or edit mode.