on your database install, run the listener, get a status of your database
> lsnrctl - status
make sure your service is there and listed
Note in a 12c Pluggable environment, you'll need to connect via the Service instead of the SID
We can't help you with user/password.
Try 'system' and the password you supplied when creating the database.
run 'tnsping myservername' using the name of the machine the DB is on and post ALL of the results.
Have you tried connecting locally with sqlplus to try to confirm the sid?
SQL*Plus: Release 22.214.171.124.0 Production on Tue Feb 24 16:58:11 2015
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SQL> conn / as sysdba
SQL> select instance_name
2 from v$instance