not able to enter OEM

Sir,
I have been deployed at one of the client place.
There they have only one server on which oracle 8i database runs.OEM is not configured here.when I tried to configure OEM by typing EMCA at command promt, It displayed a message,"Cannot find the file 'emca'(or one of its component)Make sure path and filename are correct and all required librarries are available".
This is a online database and server should not be off.
Kindly guide me how I can use OEM on the server.
Regards,
saurabh

how about look where is you binary located?

what's wrong with sql*plus :)

cant use a mouse with sqlplus :p