When the server is started, you can connect your server to Clustermin.
IP address: your server public IP address
Password: server root password, leave blank if you already added your SSH key when creating server
Uncheck the box Create user, then click Connect.
When it connects your server, it'll create and store a secure SSH key on your server. It'll automatically detect your memory size, disk size, distro name and version.
You can now manage your files and execute commands on your servers via Clustermin web interface.