Hi Kumar,
Why New GL????
The intention behind SAP New GL Configuration is to Combine the features of GL, Profit Center Accounting, Reconciliation Ledger, Special Purpose Ledger, Business Area, Cost of Sale Accounting. Benefits: Benefits like Segment Reporting, Cost of Sale Accounting, Management Reporting, Parallel Accounting, Balanced Books are possible with New GL.
Activating General Ledger Accounting To make the settings and use the functions in General Ledger Accounting, you have to activate it.
To do this, in Customizing choose Financial Accounting ® Financial Accounting Global Settings ® Activate New General Ledger Accounting. (or T Code FAGL_ACTIVATION)
And also you can find the lot of materials in Google ...1st you need check over there..before posting
any way find the some helpful document
http://sapfidocz.files.wordpress.com/2013/01/new-gl-configuration-step-by-step.pdf