I think the key here may be the following information at the very top of the howto you are consultiing
“… edited this page on Jun 24, 2013”
it is pretty old and i would be surprised whether it would still work. you can find manuals on how to install ERPNext here in this forum or i.e. here.
please be also advised that managing your own ERPNext instance which is exposed to the internet is somethign that requires quite a level of Linux system administration expertise if you want to have a safe and secure system. Many people may be better off with a hosted version of ERPNext like on erpnext.com.
This article may be an interesting read in this context