If you're trying to start a thread in the Share Your Work section, or attempting to find a beta reader in the Beta reader section, you must have a minimum of 50 posts before you can do so.
I see from your introductory post that you only joined an hour or so ago, so the moderator for the New Members section probably hasn't had an opportunity to give you an official welcome and some links for navigating the site - which will include more about the 50 post minimum.
And unofficially - welcome to AW!