David,
Go to wincustomize.com. You should see "Welcome Citizen David Smith" at the top of the screen. If not (your browser might not have cookies enabled or whatever), go ahead and log on.
Click on "Edit Account" in the navbar at the top of the screen. From the options, choose "Change Your NickName." This is the name that appears in the forums and on the Metaverse.
When you come back to galciv.com, you'll probably need to log out and then log back on (top right corner of the screen) to clear the old cookie and make sure that your new nickname is displayed.
When you post games, make sure to use your "Player Name" on the game submission screen - in your case, "David Smith" (WITH THE SPACE) - to make sure that they are correctly assigned to you. Good luck and good gaming.
We need a "sticky" on this topic.