You can't change your user name Amber, only an admin can do that, which is why it's probably coming up as wrong password. You can change the name that displays on the profiles. If you go Profile> Modify Profile> Account settings you will find the box to change your display name. You will still need to sign in using your original user name tho, but most of us pick stay signed in forever anyway.
Post back here to let me know if it worked!