Command Line Creation of a new 12g Oracle Database

I am new to creating an Oracle database using the command line. I am logged in as superuser; now I would like to create a new blank database, "mynewdatabase". $ . oraenv ORACLE_SID = [oracle] ? mynewdatabase Is there a step-by-step example of how I can create a new database instance. Most of the examples I have found on the Internet show examples with a Windows environment and not Linux. Once I know how to create the new database environment, I can use ... sqlplus / as sysdba and begin working some database magic. Any assistance would be greatly appreciated!