Don't be scared to post! As long as you seem like a decent human being, reviews will mostly try to focus on constructive criticism rather than just trashing your work.
Trying is the only way to get better.
Just show a willingness to learn and don't whine in the forums about mean comments on a story. Some of the authors here have a lot of experience and know more than you. Take their advice.
And, for guaranteed success, tag Endmaster three times in a row. It's good luck and doesn't annoy him at all.
To tag people, put @ and then their name, like this: @Bexly but with Endmaster's username