I would like to ssh to the instance of the terminal

Sure, you can ssh to the terminal while the terminal is up and running.

First of all, you need to set SSH public key into the terminal. The public keys are synced with Github when you sign up. If you add public keys to GitHub, you can sync in Setting page.

When you launch terminal, select ssh keys that you want to put in the terminal.

If you want to add SSH key manually, add lines in ~/.ssh/authorized_keys file.

# Open authorized_keys and add your public key
$ vi ~/.ssh/authorize_keys

After setting up ssh the key public keys, you can access the terminal with <username>.<hostname>.wazaterm.com

$ ssh user1@hostname1.wazaterm.com