To know about Volume Licensing, see here http://www.microsoft.com/licensing/about-licensing/how-volume-licensing-works.aspx
It is quite obvious from its name, that it is meant for Organisations (who would buy thru Volume Licensing).
You would not be eligible for the same - you would need to buy a copy of Windows 8 to install it.
However, if you purchased your PC recently, you may be eligible for certain upgrade plans. Check here: http://www.windowsupgradeoffer.com/en-US