Creating a Secure Area
The secure area is enabled on the website by changing some of the pages to password protected pages. For example a governors page, or a teachers area.
When editing a page in the Schudio CMS at the bottom of the page manager for each page there is an option to turn on password protect.
Once this has been turned on, the page can only be viewed after logging in. A login page will appear on the page before it is accessed. (This is a separate area from the admin login) It also requires a different type of user - a member user.
For your governors you could create one user account that they share (most common approach) or each individual could have their own.
Member accounts don't provide any edit access to the site, just the ability to view any password protected pages.