I first followed the getting started video that is provided once you have an Oracle Cloud account, that showed how to create the SSH keys, the instance, and open network ports to get at it.
Here are a couple of links to directions on the 3 steps above:
https://docs.oracle.com/en/cloud/paas/database-dbaas-cloud/videos.html
http://www.oracle.com/webfolder/technetwork/tutorials/obe/cloud/dbaas/obe_dbaas_QS/oracle_database_cloud_service_dbaas_quick_start.html
Then:
C:\Cloud>c:\putty\putty.exe -i myOracleKey.ppk oracle@public.ip.address
Once you have created an instance/service a public IP address is provided.
DB Express : https://yourPublicIPAddress:5500/em
APEX: https://yourPublicIPAddress/ords/pdb1
Workspace: INTERNAL
Username : ADMIN
Password : set during service creation
DBaaS Monitor: https://yourPublicIPAddress/dbaas_monitor/
Username: dbaas_monitor
Password: set during service creation
Glassfish: https://yourPublicIPAddress:4848/common/index.jsf
Username : admin
Password : set during service creation