Have you tried this site yet?

Underground Voices

It's not for teaching but sometimes the best way to "learn" or at least see if your writing measures up, is to look at the styles of others.

You might be able to email someone who was published and ask them to take a look at your writing or ask them if they could suggest a website to join. You'd be surprised how helpful people can be. (Especially if you compliment there writing)

There is a place on that site for submissions. There is nothing to be lost for submitting. Nothing at all.

I may have some more sites bookmarked. If I stumble across them, I'll send them your way.