Hi Anwesh,
please always write to the RIOT mailing list to get help!
I did the initial support for this boards more than a year ago, so the only documentation I have is: https://github.com/RIOT-OS/RIOT/wiki/Board%3A-Spark-Core
For more help, please ask kindly at the mailing list.
In case a RIOT developer from Berlin wants to have my spark to finish the RIOT support, I'm open to donate mine.
Best Christian