Follow the steps as mentioned and it will be a cakewalk.
1) Login as sys user.
sqlplus sys/sys as sysdba
2) Execute the following command. It will create ctxsys user and create necessary roles which will be granted to existing users. Here ctxsys is the password you want to create for ctxsys user, sysaux is the default tablespace, temp is the temporary tablespace, nolock is for disabling the user locking for unsuccessfull attempts.
Enter value for 1: ctxsys
Enter value for 2: sysaux
Enter value for 3: temp
Enter value for 4: nolock
3) Grant ctxapp role to
SQL> grant ctxapp to test;
4) Now login as ctxsys to create default preferences.
5) Execute the following command. It will create default preferences for your environment.
That's it we are done with it, now login to your schema to create domain indexes as shown here.