soujanya,
I've just posted a set of documents to the forums from a Webinar that I did for the OTM SIG last year. These help describe the CSV upload process in more detail and give information on how to package multiple CSV files up into a single ZIP file for easier processing. Please let me know if you have any questions.
http://www.otmfaq.com/forums/f24/webinar-improving-csv-uploads-multiple-csvs-via-zip-266/
Thanks!
--Chris