Back Row Attack equals Panic Attack!!

[rainmaker]

I've done JH volleyball for the last three years, by choice. I just don't do enough to feel comfortable at the higher levels. But this year our (new) assignor has decided that "If you're not moving up, you're moving down", and I'm doing some varsity this year. I don't feel ready, AT ALL, but I'm not going to change her mind, so I guess I'd better dig in and give it a good shot. So here's what i need the most help with: Back row attack. I have no clue how to see this, how to judge it, how to be reasonably certain, and not make an *** of myself. And I simply can't get my mind around the details of the rule, when it talks about "if the ball breaks the plane and is blocked" then you call it, or don't if it is all the way over or what?

Any and all suggestions very welcome.