If you only want to restict access to registered user this is an easy task. You just need to set the "Who can read" property in the Access control metabox to "logged in users", right on the page where you edit the page. (It should be located on the upper right on the page editor screen.) After updating the page only logged in users will be able to view it.
If you need further control like "only a specific group of users should be able to read this page", there is currently no other way than to edit all user accounts individually. Create an access area (Users / Access Areas located in the toolbar) assign it to every User you want to belong to that group (that's the part where you edit lots of user accounts) and finally select the group in the page editing screen as described above.
Hope I could help,