Installing open VPN on Ready nas duo

I have installed root SSH access add on and the APT addon but when I try to execute apt-get install openvpn it fails see below error

Dradis:~# apt-get update openvpn
E: The update command takes no arguments
Dradis:~# apt-get install openvpn
Reading Package Lists... Done
Building Dependency Tree... Done
W: Couldn't stat source package list http://www.readynas.com 4.1.14/ Packages (/var/lib/apt/lists/www.readynas.com_packages_4.1.14_Packages) - stat (2 No such file or directory)
W: Couldn't stat source package list http://archive.debian.org sarge/main Packages (/var/lib/apt/lists/archive.debian.org_debian_dists_sarge_main_binary-sparc_Packages) - stat (2 No such file or directory)
W: Couldn't stat source package list http://archive.debian.org sarge/contrib Packages (/var/lib/apt/lists/archive.debian.org_debian_dists_sarge_contrib_binary-sparc_Packages) - stat (2 No such file or directory)
W: Couldn't stat source package list http://archive.debian.org sarge/non-free Packages (/var/lib/apt/lists/archive.debian.org_debian_dists_sarge_non-free_binary-sparc_Packages) - stat (2 No such file or directory)
W: You may want to run apt-get update to correct these problems
E: Couldn't find package openvpn
Dradis:~#

I'm now a bit stuck!

Any help would be greatly appreciated

Thanks

steve