Backup database using rman (always make at least one backup even on empty database!)

sqlplus

connect as sysdba

startup nomount

rman

connect target /

mount database

BACKUP DATABASE INCLUDE CURRENT CONTROLFILE;

recover

then recover database;

Create Oracle database for Control sql backend (not available in free version)

start sqlplus: 

sqlplus /nolog
connect sysadmin/sql as sysdba
startup nomount