On a Windows 7 desktop, I've installed an Ubuntu virtual machine with VirtualBox.

On the virtual machine, I've installed OpenSSH and can connect to it from other 'real' machines on the network through its local 192.168.0.\* address.

The question is, how can I set it up, so I can SSH into it over the internet?

My ISP gives me a dynamic address and I've set-up an account with No-IP.