Creating a PostgreSQL database is a straight-forward process. All you need to do is log in to your cPanel -> PostgreSQL Databases.
In the Database Name: field enter the desired database name and click the Create Database button. Note that the database will always include your cPanel username as a prefix for the chosen database name.
If you have any PostgreSQL problems, ask your host for assistance. SiteGround offers the best Postgre hosting and we'll assist you with any Postgre-related questions/problems you may have.