If you don't have an account on sqlanywhere-forum, you can create one here. Simply authenticate using one of the options below, and then you will be prompted to enter a user name. Once you've done that, you're done! You can then ask and answer questions. If you need to log in again, simply use the same authentication provider and that's it.
If you don't have an OpenID, there are a number of providers listed at openid.net.