Login to the control panel -> go to your domain name -> go to databases -> create anew database -> create a user and password for the newly created database.
Thereafter, click on DBAdmin -> this will open PHPMYadmin with which you can use to manage your database, import, export and etc ..
Please take note that you should have pop-up blocker disabled in your browser otherwise, you will not see the new window that pops-up to open phpmyadmin.