What happens when I delete a post on Facebook?

[braveincome027]

I posted a somewhat private pic of one of my teachers on a private Facebook group. It got a bunch of likes and comments, but when my mom saw it (my FB account was still logged in to on my computer) she made me take it down (which I understand to be a smart move, now). Will those people who liked and commented on the post be notified that it was deleted? Will they ever really know that it was deleted unless they attempt to search for it and cannot find it? And what really happens when you delete something on Facebook? I noticed in their "Privacy Rights" page that they don't delete all info when something is deleted, so what stays and what goes? Thanks for helping me out.