Edit repository list, update apt-get, get the key and install webmin.
sudo vim etc/apt/sources.list
deb http://download.webmin.com/download/repository sarge contrib
wget http://www.webmin.com/jcameron-key.asc
sudo apt-key add jcameron-key.asc
apt-get update
apt-get install webmin
https://localhost:10000