Could someone please explain me how to configure "SNMP Polling" for splunk installed on windows Server 8 R2 machine ? (From Scratch)
There is a Splunk app for that:
The SNMP Modular Input
If you mean your Splunk server is Windows 2008, that shouldn't matter.
Log into your local Splunk installation
Near the upper left, click Apps then Manage Apps
Click the Browse more apps button
Search for SNMP
Click the Install button for the app SNMP Modular Input