I am new from yesterday to this forum…
Since yesterday as well, I have a VPS running on Ubuntu 14.10 (64 bits) system, and I am about to install Virtualmin on it.
In general, installing Virtualmin is just a matter of running the install.sh script on a freshly installed version of your distro.
That install.sh script will install Webmin, Virtualmin, and all of it’s dependencies.
It looks like that link you’re looking at there does have you run the install.sh script.
When it’s time for updates, they’re placed into the apt repository on the Virtualmin site. When you run an “apt-get upgrade”, you’ll receive the new Webmin/Virtualmin versions.