Restricting viewing of posts and categories to certain readers

I’m unable to search (I get “We couldn’t find anything!” whatever I search for), so apologies if this is already covered elsewhere. Just give me a link if need be.

I want to restrict some of my posts and maybe a separate category altogether so that only my friends and/or family can read them. What’s the best way to achieve this in v2? I guess I’ll have to make sure all such readers are registered too?