Clicking on TNSNAMES.ORA? What is this supposed to do?
Did you make sure that Oracle database is up and running? Can you connect to it through SQL*Plus (run from D:\oracle\ora90\bin)? If so, everything is fine with the database.
Now go to D:\oracle\ora90\network\admin, copy TNSNAMES.ORA and SQLNET.ORA and paste them into the E:\oracle\ora90\NET80\ADMIN. That should be enough. If not, you can always use Net Configuration Assistant.
Also, it would be a good idea to maintain only one copy of TNSNAMES.ORA. In order to do that, create environment variable called TNS_ADMIN and point it to a directory which will hold TNSNAMES.ORA file; for exampleC:\> SET TNS_ADMIN=C:\MY_ORA_FILES