How to review version history

1. Click at the top left corner of your screen.
2. Enter your user name and password to log in.
3. Navigate to the content item whose history you want to view.
4. Click the history tab on the green edit bar.
   A list of previous versions will appear, with details about their creation and the tools to compare or revert to each version.
   
5. To see what a particular version looked like, click the link. Scroll down to see the version.
   

To read more about page editing history see the Versioning section of the Plone 3.0 User Manual.