Gordon,
Down in the forum, there's a folder called Share Your Work. It's password-protected so that no publisher can ever say your work has been published in any form, & you can, of course, remove the post anytime you want.
Nobody wants to steal your work. I promise. It's not 'cuz I don't think it will be good. It's because it's unpublished & unpolished (as you are on the rough draft). The chances of someone wanting to steal from an unpublished author are incredibly slim, & the chances of them taking your first chapter & recreating your novel, nonexistent.
But it is up to you. Don't share 'cuz you want to validate yourself to this board, but because the feedback you receive will help you out. You will be able to see how readers & how those in the field respond to your work. That is the purpose of the SYW forum. If you put a piece up that you don't want critted, you will only get your feelings hurt when it is critted (& it most likely will be). And if you put it up there solely to prove you are a natural writer to yourself & those in that particular thread, I guarantee that at least one person will go in there & say you are not, probably because they didn't like your style, your genre, or what they can see of your story.
So my suggestion: post an excerpt of something you would submit somewhere. But don't post unless you want constructive criticism.