I am using Oracle for the first time.I installed Oracle SQL*PLUS ver 8.As I had to learn this for an exam. But I am facing the following error after I enter it with the system default scott/tiger ...

"ORA-12203: TNS:unable to connect to destination"

Sorry ,if this question is already asked as I searched, but didnt get.
Thanks in advance

Check if the oracle service and listener services are up and running.

Also ensure that the account is unlocked and has permission to connect to he database.

What does "Check if the oracle service and listener services are up and running." mean ???

there will be 2 services running in the server on which oracle is installed.

1. for oracle database service.
2. for oracle listener .

I have installed on my PC itself to learn it ,so the server what your saying is localhost for me ,so what do I do to check and make those services running .

check in services on windows machine .

I could see 4 oracle services namely :
OracleClientCache80..........Started..........Automatic
OracleServiceORCL..........Started..........Automatic
OracleStart ORCL
OracleTNSListener80..........Started..........Automatic

What should I do now ?

Now the services are running.

Ensure that the account is unlocked and has permission to connect to the database.

and buy a book "beginning Oracle administration" or something like that...

How do you ensure that the account is unlocked and that it has permission to connect to the database ???

I am desperate to start it so....asking so many questions
Sorry

Do you have access to SYS or SYSTEM database account ?

Login from that and check.