Yes, there is. Right now you're classified as "fresh bread"; this means you can't post new threads or have an avatar of your own. Once you have posted ten times in places other than Tea with Mr. Tumnus, the fan threads, and Dufferland, you'll be classified as a junior member, and you'll be able to post new threads if you want to.
The post count stuff confused me at first, too; but ten posts, and you should be able to post your story thread.
I'll look forward to it!