Pretty simple, really. I'm not sure about the "exact" way from a buyer's login, but it's something like this.
Start at the home page. Login to your account. In the top, right hand corner, click on My Trulia. Then, click on "My Listings." From there, you should have the option to submit a listing. After that, it's pretty much just "Fill in the blank."
Good luck on that house! Out of state buyers are really getting active in the Madison and Huntsville areas right now.