Making a page require a user to login.

I’ve been trying different kinds of plugins for this but there doesn’t seem to be one that works as I need — at least not with the theme I’m using (Suffusion).

How do you make a particular page check if a user is logged in and, if not, redirect them to the login page?

I have a ‘members only’ home page that’s different from the public blog page. I’ve tried making that page private, but it doesn’t work. I can still access the page without being logged in. So how do I put the necessary code in the members’ page to check if they’re logged in?