(Posting my new-user reply again.)

When you registered you clicked to accepted the terms that were given on the 1st registration page:
Fusor Forums - Registration

That page contains the same rules as what is listed here:
Board index - Announcements - Announcements and Site Administration Topics 
Fusor.Net Policies and Procedures
http://www.fusor.net/board/viewtopic.php?f=47&t=10508#p69690

and specifically [b]The Rules: #1[/b]
The forum rules require you to use your full name as your username. If your name is John Smith, your UserID (i.e. login handle) must be John Smith, or John_Smith. This is the name that will appear in the forum listings. “JSmith” or “JohnS” or “JS997” or “handles” like “MrFusion” or “ProtonBoy” are NOT permitted.

Also there is: [b]The Rules: #2[/b]
New members are required to introduce themselves in the [b]"Please Introduce Yourself"[/b] forum prior to posting elsewhere on the site.

You have not complied. Please change your username to comply.

[b]Changing your Username[/b]

Here's how:
[list]
[*]Login to the board
[*]click your current username in the upper-right of the main page and select [b]User Control Panel[/b] from the pull-down
[*]In the tabs at the top, select [b]Profile[/b]
[*]At the left column, select [b]Edit account settings[/b]
[*]Edit the [b]Username:[/b] field to be your full name
[*]Type your password in the [b]Current password:[/b] field (near bottom of page)
[*]Click [b]Submit[/b] button at bottom
[*] Note: After you change Username, the new name becomes what you use to login to the Forum. Your password should remain the same.
[/list]

I also suggest adding a Location to your profile. It can help to know generally where a member is in the world to adjust a response to them. I have used my City and State, but if you are worried it could be more general -- just State, something like Central USA, just your Country is better than nothing.

[b]Adding a Location[/b]
(Skip the first 3 steps if you are already in the Profile section from doing the Username update.)
[list]
[*]Login to the board
[*]click [b]User Control Panel[/b] near the top of the main page
[*]In the tabs at the top, select [b]Profile[/b]
[*]At the left column, select [b]Edit profile[/b]
[*]Edit the [b]Location:[/b] field
[*]Click [b]Submit[/b] button at bottom
[/list]

This Location information will appear in the right column, under your name, when you post.