Attention: If you don't want the email address you used to register on the site to appear on posts, do the following:

1.  Log into the Sandlot site as usual, with your email address and password.
2.  Click on the Account tab on the top of the web page.
3.  Click on "Update your Profile."
4.  Then click on "Contact Info" and there, you should see a place for your forum username.  Your email address might appear so go ahead and delete that and then type in whatever username you wish to use for posting on the forums.  The site will check to see whether the username you choose is available.
5.  Also log off then log back in so that any posts you make have the new user name.  (Thanks to Westward_Sass for adding this information.  )

I hope that this helps everyone. 

I moved this from the website support subforum temporarily. 

(Edited by Mjay to change title & warning triangle)