Hey John... I investigated a bit and it seems that users of the forum can't change the name of users on the forum. I hope none of the A-Shell software developers set up systems that are so apparently dumb, arbitrary and counter-intuitive as that!
In order to change your display name, you have to request it of a moderator, which is Jack or me. So let us know the desired name and I'll change it for you.
Though I should point out that any hope you may have had for anonymity is now pretty well destroyed. If you're hoping to leave "John A" behind and come back as The Green Lantern or the Mighty Sword of Cutting-Edge Programming, everybody's going to know it's you...