Where can I find my TNSnames.ora file?
The TNSnames.ora file is created when you install your Oracle client and, by default, is stored in your Oracle Home directory. You should check with your DBA because some organization may have one central location on the network drive. However, in general your TNSNAMES.ora should go into the \network\admin directory of your Oracle Home. So if your Oracle Home is E:\oracle\product\11.1.0\client_1\, then you should find it in E:\oracle\product\11.1.0\client_1\network\admin.