Lord Ganpati is the son of Lord Shankar and Goddess Parvati. In Hindu culture, Lord Ganpati is believed to address all his devotees and remove all their obstacles. That is why he is called Vighnaharta. So, if any devotee is going to start a new business or any new activity they perform Ganpati havan. 

An idol or portrait of lord Ganpati is placed in front of havan and is decorated with flowers, jewelry and other decorative. During the Havan Ganesh Mantra is chanted by both pandit and devotees. At last Ganesh Aarti is performed and devotees seek blessings from Lord Ganpati. The Ganpati Havan can be conducted on any auspicious day. However, the date for havan is decided according to Nakshatra, yog and Brahma Muhurtha.