You can change the display name for users on your site. To edit your own user account, click on your name in the top right of the screen. To edit another user, navigate to the Users → All Users screen, and click on the user you want to edit. You will arrive at the edit profile screen for the user
User Display Name or Nickname
Locate the Name fields. Type in the first and last names, as well as a nickname. Now these will appear as options you can select as the display name.
Usernames cannot be changed by default, but here are some ways you can do so.
Biography or Profile Description
A little further down the page you’ll find a space where you can enter a bio or description for the user. This bio may be displayed below your blog posts.
User Profile Pictures
WordPress does not support user profile pictures by default, however it integrates with the Gravatar service (learn more).
You can also use a plugin that add the ability to upload a user profile picture, for example WP User Avatar or User Profile Picture.