oracle username,password

i have installed newly version of oracle9i, when i open the sqlplus editor, and give username and pass as
username=scott
password=tiger

it gives error as "PROTOCOL ADAPTOR ERROR"
if i give hoststring
host string=localhost

it says, "could not resolve service name"

This error occures when your service is stop, plz start your service. If you dont have any service to connect wuth database, create new one.

yes i have start my service, can u mention which service should run must, i have 7 services running, at a time.
and does username and password are correct, is there any need for host string as well , i am using it in personal pc.
I installed it not as server application but custom.

how to create the service ? culd plz explain a bit

To create a new service, you can use the one of the following method

Method 1:
---------
go to the oracle_home\network\admin and add the following commands in "tnsnames.ora" file, for example my database name is 'PROD' and my computer name is 'mycomputer':

PROD =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = mycomputer (PORT = 1521))
)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = prod.world.com)
)
)

Method 2:
---------
Oracle also provides graphical interface such as for Oracle8i 'SQL net easy configuration' or 'Net8 easy config' utility, for Oracle9i, i think you have to use 'Oracle Net Manager'

Regards,

I had the exact same problem as poppy 123 did.
i need full detail as to wat service shud b open n abt your last reply for the net configuration thing, i hav that file, but it's not working. where is tnsnames.ora? i need explanation to everything that u hav explained to poppy 123. (Sorry, i'm a newby ).
By the way, i'm doing all my work on Win XP.
The default username is 'scott', password is 'tiger' and hoststring is empty rite? on the home pc?
Please i need to practice on Developer Form 6i. So do reply soon. My finals are in the end of December. I need urgent help in this matter.

Do a search for *.ora in ur system..those are not a large number of files..
listener.ora
tnsnames.ora
init.ora
and there will be some more....the number of these files
will increase one by one as u will be adding the databases
one by one...
there will be one initORACLE_SID.ora for each oracle_sid(database)..

Read those files ...
you will definitely get a lot of idea...
bye.........