Go to your 000web-host control panel
Under "Software / Services" click MySQL
Set up your MySQL with your chosen username and strong password then click "Create database" > then go to the following page via your website - http://example.com/wp-admin/install.php
You will be asked for a database name, database user, password, host name this will be displayed under "MySQL via 000webhost control panel" complete the instalment process.
Then you have your first WordPress based website!