I'd be careful sending out your common app essay online, even on CC. I'd love to read your essay and have you read mine and get some critique on it, but I can't be sure that you won't copy my essay. Likewise, you can't be sure I won't try to steal yours if I like it.
Look some more on CC, there are forums and topics on how to safely have your essay read by a professional without being ripped-off by scams. Or you can just have a teacher or someone you know in person read it. Try finding someone you don't know all too well but who will read it and give you an honest opinion on what they think about your essay.
Hope you find the help you're looking for!