100 % Review Forum How to review?

I am the newest of newbies and am open to constructive criticism. While willing to review others' work, I don't have a clue as to how it should be done. For example, ratings appear to be on a 1 to 100 scale. Is 50 average or failing? I couldn't find an FAQ that discusses this issue. Thanks in advance for reviewing Oogie: a casualty of the Sexual Revolution.