When you first join the site your [display name] is your [username] as selected on [registration]. To change this goto [Profile] in user menu and enter [First] and [Last] name, scroll down and select [save profile] button, after the saved message has appeared refresh the browser window or click the [Profile] menu link again. Now set [Select Your Public Name] from the drop down you will see a better selection of options, this is the name that will be used in the contact forms.
