Multivirt India Pvt Ltd
You can use the online method to activate your license here:
Or you can can call Autodesk Product Registration and Authorization:
1-800-551-1490 > Option 1 (English) > Option 1 > (Stand-alone)
Asia / Pacific: 65.6735.5688
Europe / Middle East / Asia: 41.32.723.9595
You will need to provide your serial number and the request code.
I have sent you an activation code via Private Message (click on the envelope by your screenanme at the top of this page).
Like DarrenP said, please do not post sensitive information such as your serial number in public forums.