Thanks to this forum, I've sorted out most of my problems, and in one case the solution was obvious after only a day of staring at it. I do have one problem. Most of the website is meant to be visible to the public, but one page is meant for members only. I can't see anything under "Permissions" to make this possible. Is it?

Also about permissions, I don't understand how they are enforced. There's no mention of a password. If I try to access a members-only website, how does the system know whether I'm a member?