Functional Developer


I'm new to ERP functional consulting. I've joined as a technical developer and now they put me in Functional side.

I'm from technical background and it's bit difficult for me to understand the Ledger,Journal,BalanceSheet. 

I'm using AX2012 R3, their is no particular module in which i have to be perfectionist. But i need guidance with what or from where i can start to become functional developer. 

Please suggest :

As, I'm from core technical background.Which module i have to start with ?

Which book i have to refer for Functional aspects(Basic understanding) ? 

Any online material or website ? 

I'm new to this forum. Lets help each other and contribute this forum to grow like stackoverflow and codeproject.


Vidur Bakshi