Trouble sshing into my VM instance

I am trying to monitor my training using tensorboard.

Which IP address should I be connecting to, (external, internal)... and the is the username my username for my GCP account? Or the username for my local machine?

Right now, using the external IP address gives me Permission Denied (publickey), and using the internal IP address gives me either connection refused or operation timed out.

Any help would be appreciated. Thanks!!