Hmm, it's probably not a good idea to send your article out into the wild for spelling and grammar checks, because there's no telling if someone might reuse it or something. Also, it no longer becomes unique if you make it available on other websites. Unless you plan on selling usage rights only, keep the article private and upload it only on constant-content.
The forum veterans here can help you with grammar, but they can't check the entire article. You can post snippets if you want and get positive critique.
Here's what I did when I first started out, maybe it can help you:
I took a week long break after getting two successive rejections and studied grammar. Specifically, I used the Video Aided Series: English Grammar DVD's. It's an awesome teaching guide for a quick refresher. However, it's only for foundational grammar, so it won't make a master out of anyone. If you don't have this video series, then any grammar book will do.
The week-long study improved my success rate in CC, but what really tipped me over the edge was when I used the Windows Speech program in the Control Panel and let Microsoft Sam read out my entire article. I know it sounds weird, but actually hearing my article out loud has a profound effect on my proofreading. You can achieve the same results be reading the article out loud yourself or letting someone else read it for you, but for me the computer voice is very useful since you can see the words highlighted one by one and adjust the rate of speech. The only downside is the monotonous, guttural, E.T.-like voice, but I eventually learned to like it.
It's nice to let someone proofread, but what you really want is the ability to proofread yourself. By studying and using the Speech method above, I've increased my ratio from a 66% rate of acceptance (for every 3 of my articles, 2 are accepted and 1 is rejected), to about 90 % (so far. I hope it improves

). The only rejection I received since that time was a title problem and unrelated to grammar or spelling.
Sorry for the lengthy post, but you get the picture. Probably best to take the week off right now and brush up on your skills. It will do you good in the long run. Best of luck.