Your MySQL databases can be fully managed from the MySQL Databases page. To create a database just find Hosting → Manage → MySQL Databases:
In the section Create a New MySQL Database And Database User, enter your MySQL database name, username, password and click on Create:
Once done, a new database will appear on List of Current MySQL Databases And Users section and you will be able to manage it freely.
The first part of the database/user name (u123456789) is unique and cannot be removed or changed.
Password must contain at least one number and one uppercase and lowercase letter, and at least 8 or more characters.