Turn Dynamic Horizontal Chart into 12-month rolling

Hello I am having trouble turning the Dynamic Chart attached into a 12-month rolling chart. I am not very familiar at all with the Offset formula as well as Ranges and would greatly appreciate it if someone can help me. I created a very simple dynamic chart which has been modified from the most commonly known out there to work with horizontal data and Vlookups, thanks to Andy Pope from an older post linked below. I would like to know where to insert code into the Range formulas (CTL-F3) which would create a 12-month rolling chart. Thank you once again to any that could help!

Referenced old thread
http://www.excelforum.com/excel-char...tal-table.html

Vertical Dynamic 12-month rolling chart (w/out Vlookup solution modification)