Ada-

You can change your icon in the avatars section of the profile. I uploaded the one I had after making it. You can resize photos to use as well. Just go to Profile, then click Avatars and then at the bottom it has an area where you can browse your computer for images. OR you can use several of the ones they offer here.

As far as your log in name-you have to get a moderator to change that. You can PM one or go to the Technical Questions forum and post there that you want to change it.