docs:
https://docs.oracle.com/cd/E11882_01/server.112/e25494/create.htm#ADMIN002

so:
http://stackoverflow.com/questions/9534136/how-to-create-a-new-database-after-initally-installing-oracle-database-11g-expre

with dbca:
https://docs.oracle.com/cd/E11882_01/server.112/e25494/create.htm#ADMIN12479
http://www.fehily.com/books/createdb/createdb_oracle_11g_2.html
dbca
    -help
    -silent -createDatabase -templateName General_Purpose.dbc -characterSet AL32UTF8 -responseFile NO_VALUE -emConfiguration LOCAL -gdbName ihorcl -sid ihorcl

# ask for SYS, SYSTEM, SYSMAN pwds

# -gdbName          global database name
# -memoryPercentage 30 

Look at the log file "D:\dev\utils\oracle\cfgtoollogs\dbca\ihorcl\ihorcl.log" for further details.

 1) Set the environment variable ORACLE_UNQNAME to Database unique name 
 2) D:\dev\utils\oracle\product\11.2.0\dbhome_1\bin\emctl.bat start dbconsole

Global Database Name:ihorcl
System Identifier(SID):ihorcl
The Database Control URL is
    https://<host>:1158/em

with create database:
https://docs.oracle.com/cd/E11882_01/server.112/e25494/create.htm#ADMIN11073