$ gcloud compute ssh [--project=PROJECT_ID] [--zone=ZONE] VM_NAME
Here is a list of VMs that are available for the Project
If you have already setup the default project and zone for the gcloud cli, you may only need to specify the vm_name. e.g.:
$ gcloud compute ssh lt-gp01
Otherwise, please put the project_id and zone as indicated above.
Please try to do your work under your user directory unless you're working on the changes that applies to all users.