Official Dreamhost Guide can be seen HERE
How to log into phpmyadmin
Once logged into your Panel , go to the MySQL Databases Page. If you have not modified the toolbox, you will it it listed:
or you can find it under Goodies -> MySQL Databases:
What you will see on the next page:
To get your Database password for the Database User , click your user. On the next page you will be able to retrieve your password:
phpMyAdmin is where you will log in. Your domain has to be hosted with dreamhost. All of the Hostnames are all interchangeable, so you do not have use use one specific to your domain, just a hostname setup.