NLS_Date_Format Setting in Oracle 9i

Hi there!
I am hereagain with yet another doubt. I am in the installation of our project in Spain. Installation and all other preliminary things have worked out successfully. But then, the initial proceedings to this project stands hindered, becos of the fact that the project doesnot save the records for varied treansactions that involve date to be saved.
I have found that as according to the territorial language of spain, the date format has taken the default setting as dd/mmm/yyyy. But as according to our project we need the format to be dd-mmm-yy.
For your info we are using oracle 9i and MS Visual Basic 6.0
I am given with the solution to change the same in the init.ora file of oracle which i will find in the server, by changing the NLS_DATE_FORMAT="DD-MMM-YY"
But I donot know how to exactly proceed with this, as I have never done this before and if I do make a slightest error the result will be very enormous. So could any of you suggest how I could do this systematically, or if you have any other way to this problem, then please let me know as I am very confused about this and it is very urgent.
If you do have any solution links to this problem do let me know.
Awaiting many a reply
regs
Abigail

Changing the init.ora (NLS_DATE_FORMAT="DD-MMM-YY") seems to be the best solution.
The risk you take by changing it is minimal, since it only means the query results is formatted in a certain way.
You can also explore: alter session set nls_date_format='DD-MMM-YY'; which changes the format just for a particular session.
You can also explicitly format your result set at query time, as in SELECT TO_CHAR(SYSDATE, 'MM-DD-YYYY HH24:MI:SS') "NOW" FROM DUAL;

Regards,
Dan

Thanx Dan.
I tried changing the format using the alter query, but this lasts only for a session. I would like to know how we have got to change the same in the Register of Windows ie in the HKey Local machine -> Software-> Oracle->Homes. As this I came to know will give a final and lasting solution. Please educate me in this regard.
I need this and it is top urgent. I am expecting many a reply and suggestions.
Rgs
Abigail