Hm, well, I don't see a text box on your page -- but if it's empty then I wouldn't be able to see it. Do you have an empty box there with an "edit" button? It could be anywhere in the center column (or maybe even on the left if you might've moved it).
Actually, I remember being confused about this too---though that's usual for me. I did manage to put some kind of "profile" up---Snail Mail Junkie in Need of a Fix"---but I'm not sure if I did it right. Anyway, it seems to work. Like Rick said, maybe the key is the "Edit" button.
Yeah, there should be a text box that if you click around it it will show an edit button and you can move it around the page, too. If you don't see it, look in applications (under your photo) and I think there is on ether you can add.