You can choose which areas of your site to password protect. Once logged in to the admin area click on the "Add-ons" option (the one that looks like a puzzle shape) in the black navigation bar at the top of your screen (also shown below).
Click on "Options" button for the section that you would liek to password protect. Within the options box (see image below), you can choose whether to password protect the section by toggling between a green tick (active) and red cross (not active).
Please note that each of you team administrators can choose their own password protection options for their own team pages. You can amend your passwords via the main 'Settings' page (see image below).
The settings page will also allow you to apply password protection to your 'images' and 'documents'. Find out more on this by clicking here.