Lambda the Ultimate

I'm working my way through An Introduction to Lambda Calculus (Barendregt & Barendsen, 1994) and I was wondering if there is an answer sheet available, or a forum where I could talk with someone about the problems in the text. In particular, problem 2.11

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    ∀ C[, ] ∃ F ∀ x Fx = C[F, x]

and take another look at the exercizes 2.8, 2.9 and 2.10

has me stumped. I don't understand the bracketing convention used following C, and I don't get what's so special about the result shown in this exercize.