Hi Gaurav
Tim is right. I, too, am an Ariba Professional providing support to a company that has implemented Ariba Buyer 8.2 to service the needs for indirect procurement. I sense you too are working in a support project, is that right?
Anyways, if you or any of your colleagues have a connect account, you can view the Ariba Documentation over there.
But there is an alternate option. The product version that you are using also provides a link to the documents in the 'Help' section. That is where I got the documents for my training. Besides a few webinars.
Check out if you can download the documentation at your end.