1. you need to be using "localhost" or "127.0.0.1" as the hostname for your database
2. you need to create your database beforehand via the MySQL Databases link in cPanel. After creating the database there, you need to also create a database user that has access to that database.
3. since you're only allowed 2 databases, it's recommended that you utilize any "table prefix" option that the script may offer, as this will allow you to easily install multiple scripts using only one database.