On the Admin Panel Pages , Add Page/Edit Page sections, you can set any page to have Restricted Access, for only Members and/or Member Groups you choose. Scroll down this page to the Access section and just select the members and/or member groups you want to have access to that page. If you choose the "All" option on either list, or the "None Set" option on both lists, any visitor will have access.

You can also restrict access for actions within the built-in apps on the Add or Edit Page. When creating a content type for Articles on the Add Page, for example, scroll down the page, checkmark the box to “Allow article postings” for this Article Category, and options to restrict access to post articles and view articles by member groups are displayed.

You can Manage Members and Member Groups directly from your Admin Panel under the Members tab.