sungoddess...Are you using a hosting provider for the site? If hosted you may need to contact the tech support team of the provider or look through their FAQ to see if they state what the address is of the sql server and to be sure they support "remote database connections". If they want to know, Blogg-X is using the JDBC database connector from the MySQL team. I know my hosting provider has the SQL servers on separate systems from my dedicated IP address so I have to use the IP or name of the SQL server.
Basically what Blogg-X needs is the hostname or IP address of the MySQL server that your site is using. For Joomla!/Mambo this may show localhost which is fine for Joomla! because the website is running on the same computer as the MySQL server but Blogg-X is connecting remotely and doesn't know where the MySQL server is until its given a valid address.