You need to register a user name in order to post on the boards, even if you had a name on our old board.
The link to do this is at the top of the page.
Also, once you sign up, you can edit your profile, set your avatar (that little picture by people's names), add a signature, and change a few other user settings.
To do this, click on the My Controls link in the upper right hand corner.
If you have questions about any of the other features of this new message board system, feel free to ask..