How do I? in Juggling with Hedgehogs

I haven't a clue how to make my entries 'members only'. I don't intend to do that with a lot of them, but you never know. I might only want to talk to my old OD buddies (which frankly, is probably all of you) rather than the whole general public of the whole wide world.

Haven't a clue how to do it, can't find anything to click or select or whatever. I am finding this site mucho confusing.