Shukra Dwadashi Vrata is an auspicious austerity observed on Dwadashi tithi which falls on Friday (Shukravara). Dwadashi is the twelfth tithi in each Paksha (fortnight) of a month in Hindu calendar.
Lord Vishnu is offered Shodashopachar Puja on this day. Special recipes are offered as Naivedya.
As per the Puranas, Shukra Dwadashi Vrat Katha is associated with a story of a Brahmin who lived in Vidisha city (on the river banks of Vetravati). The Brahmin who performed Shukra Dwadashi Vrata helped a ghost in getting Moksha.
how vishnu puja is done on dwadashi tithi?