How can I Protect an entire Category or specific pages?


I want to protect some content for members only but I don't see any options where I can protect the content, for example if I want to protect and entire category, how can I do that? or a specific page?

I have some content restricted on the site which was done by my developer, for ex this page

But now that I added some new pages I don't know how to protect them and I can see any difference from the protected page from a regular page.

Thank you,