Hello Usha ,
celebrating festivals at office is nice concept to bring people close and enhance culture of the organisation
you can first create a cultural group with members who can help you out and are innovative .
list some events to be done on the day , ask someone to perform or arrange your local food items served on the day , you can arrange them from market but do count your attendees .
draft a mail and send it to members with fixing it in notice board too .
invite all your employees to gather on arty hall or any room you can arrange .
also invite your business /cultural /PR head as guest .
have some cultural programmes arranged for it .
have some prizes for distribution .
have some games too .
this way you can easily let people interact an a nice manner ,
at the closing you can gift all member foodies famous on the festival and close the program by wishing them for the day .
hope my suggestions will work for you
regard
Arvi