You can password protect individual pages or your entire site.
First you have to activate password protection by creating a password. This is done using the Site Password field found under the Settings tab. Save your changes when you're done.
Setting a Site Password automatically password protects your entire site. If you only want to password protect specific pages, you'll now need to make adjustments under the Pages tab.
Select each page you do not want to protect and set the Visibility to "Site Password".
If someone tries to access that page, they'll be prompted to enter your password. Note that the password must be entered exactly as written in your site's Settings section, including any capitalization.
Each site can only have one password, no matter how many pages are protected. And once a visitor enters the password for one page, they'll be able to access any other password protected pages until their session is over (when they close their browser) - after that point they'll need to enter the password again the next time they visit a password protected page on your site.