Oh, I see. I'm not sure critiquecircle is what you want, then. Most of the writers there are working on short stories or novels. I don't know if the site is capable of handling comics. Poets have to look elsewhere, as well.
As far as someone stealing your ideas... first, let me remind you that ideas can't be copyrighted. Words can. Second, many writers harbor the fear that we will be ripped off. If you want to publish and share your stories, you gotta find a way to deal with that fear and be on your toes about finding plagiarism. Did you read about
Cooks Source? The whole internet came down on this magazine editor for ripping off a blogger. Yes, some people steal. It's a drag. Thankfully, MOST people are honest.