How To Establish Administrator Authentication to the Server?

This is Step 2. There are two ways to establish administrator authentication to a new database.
Use a password file.
Use operating system (OS) authentication.
Using OS authentication is easier on Windows system. If you used your own Windows user
account to install Oracle server, it will put your Windows user account into a special Window's
user group called SYSDBA. This Window's user group will be fully trusted by Oracle server with
SYSDBA privilege.
To continue with other steps, make sure you logged into the Windows system with a user account
in the SYSDBA group.