Your MySQL databases can be fully managed from the MySQL Databases page. To create a database just go to Websites → Manage, search for MySQL Databases on the sidebar and click on it:
Choose the website name to which the database will be assigned from the left drop-down menu:
In the section Create a New MySQL Database And Database User, enter your MySQL database name, username, and password, then click on Create:
Once done, the new database will be assigned to the selected domain automatically and appear on the List of Current MySQL Databases And Users section, where you will be able to manage it.
The first part of the database/username (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
Each database can only have one user. If you need multiple users, you can consider a VPS plan