there could be 100 reasons why you can't connect, without any indication of what you have installed? how you have installed? error messages? have you created a database? have you created a listener service? is the service running? .........and the list continues.
I found the solution for this problem after many trials
for the personal 9i the solution is to start the listener manually - and to set the listener parameters manually.
but for the 10g express the listener is started with the db and the sid is always -xe-
thanks for you all