I think you're probably talking about the signature line. Click on "my profile" at the upper right of any page and scroll down near the bottom, and you will see where you can create yours.
That's correct. Just post a bit more and it will appear.I think it must be something that only becomes available after a certain number of posts or something because when I click on other people's profile and scroll down past their pictures I can see where they added their sig line but option isn't on my profile page. I can add pictures, though!