First, HCS runs a useful tool called phpMyAdmin at https://www.hcs.harvard.edu/phpmyadmin/. You can view and modify many of your database settings here. You can also access your MySQL database from the command line by typing
mysql -h mysql.hcs.harvard.edu -u group-name_here -p
at the command prompt. Enter your MySQL password when prompted.
Some settings you would use in connecting to the database in a php script:
DB = group_name DBUSER = group_name (same) DBPASS = your_mysql_password DBSERVER = mysql.hcs.harvard.edu