1. Set your environment to your Oracle 12c database home.
2. Currently no tnsnames files exist in the <oracle_home>/network/admin directory
3. Execute netmgr
4. The net manager will open. Click on Service Naming then click the plus.
4. Entry the net service name you want and click next.
5. Select the communication protocol and click next.
6. Enter the host name and port and click next.
7. Enter the service name for the Pluggable database and click next.
8. Click the test button
9. The test button defaults to testing with scott/tiger we can see how long this utility has been around. Click the change login button to change the credentials.
10. Set the username and password credentials for the Pluggable database click OK.
11. Now click test and this time the connection will be successful. Click close.
12. Click finish to close the net service name wizard.
13. Under service naming you will see your service configured. If you need to add more service names just repeat the same steps above if not continue to step 14.
14. Click file>save network configuration
15. Then click file>exit to close net manager.
16. We can now see under $ORACLE_HOME/network/admin the tnsnames.ora has been created.
17. When we more the tnsnames.ora file we can see the three service names I created have been written to the tnsnames.ora file.
18. Now we can connect to the pluggable database using net service name.