Die and look next to and under death. If you see an hourglass, click it. If not, keep dying. When you do, search around for a litte bit. if you find a porlal, go in. Keep doing that until you see Twilly come up. Talk to him. When you pass what he says, type in the desired new name. Log out then back in. You will have a new name.

Note: Easiest way to die; go to the rip in the sky, go to the library in it, hit the curved thing in the library, then go in. Hit the scroll next to the smoking one. Battle Carnax 1 on 1. Your dead! :P