Adding everybody as users to the WordPress site, I settled on using last names as a unique login. (I would have used first names, but we have some duplication. And I loathe AccessIDs.)
You cannot change the username I gave you yourself. I will be happy to do so if you email me.
However, you can change everything else about your user, including the email address you use: hover over the menu at top right that says “Howdy, <name>,” and from the drop down select “Edit Profile.” There, you can enter (or not) your actual first and last names, your nickname, and how you’d like to appear on your blog and in comments.
Your first order of business in your new blog should be to set this up in a way that makes you comfortable.