Upload a file/folder on the Virtual Machine

How can we upload something on the virtual server?

You can use SCP on linux or Filezilla. Use the credentials from the email, don't forget it is on port 22 (SFTP) and not 21 (FTP). The VM is only running a SSH server and not a FTP one.

You may also use Tunnelier (http://www.bitvise.com/ssh-client) that offers you both Shell and File Transfer access (and, by the way, is known to be quite faster than the others secure file transfert clients).