Setting up private pages, password protected

I want to set up a few private pages restricted to working group members on the Inequality website. It would need to be password protected. Some of these people are Yale faculty, some not, but they are already listed as authenticated users. They want this private online space for posting documents, discussing plans and findings, drafting collaborative grant proposals, posting updated ideas briefs, and the like. Initially, it would be just for internal working group use with the option of later creating a more public commons.