Your question is not clear. Do you ask why do we celebrate Diwali or how do we celebrate Diwali? However, I will answer both the questions in brief:
1. Diwali or Deepawali (Line of Lamps) is the major festival of North India. It is held to commemorate the return of a very loved prince Rama (who is considered to be the seventh incarnation of Supreme God of a section of hindus, the Vaishnavas, worshipers of Lord Vishnu). Though the celebration is not restricted to just the Vaishnavas and all hindus celebrate it. Rama returned after a 14 year banishment to fulfill a vow given by his father to one of his queens. Immediately before the return, Rama had fought a war with the most evil king of his time, Ravana, and killed him. The victory of Rama over Ravana is celebrated as another major festival, known as Vijaya Dashami (the victory of the tenth of the fortnight). Rama later ruled his kingdom for many years and is remembered as a king in whose reign, none of his subjects were unhappy.
2. As I mentioned, we celebrate Vijaya Dashami a few days before Diwali. At that time three paper statues of Ravana, his brother, and his son, are made and stocked with fire-works. In the evening these statues are lighted before the populace. This symbolises victory of good over evil. The story of Rama is played out in every locality for 14 days. People get their houses renovated or painted before Diwali, useless junk is thrown away, so that every thing should be spotlessly on Diwali. Diwali is a great time for business (just like Christmas in West. People make their valuable purchases during Diwali. Two days before Diwali there is a subsidiary festival when all people are supposed to buy something from the market (if not jewels and ornaments, then at least a few things for use in the kitchen). The night before Diwali, gambling is considered auspicious. On Diwali day, merchants do not conduct any business, however the shops are kept open. After an evening worship at the shop and work-places, people come to home, conduct their own worship. Then the fire-works are lighted by all households. It is a noisy evening and the celebrations continue till mid-night. People may eat at home or go to acquaintances and relatives to wish them. The day next to Diwali is known as Govardhan (increase in live-stock) and in villages the live-stock is worshiped. Though in cities, there is no live-stock, still the occasion is celebrated by lighting lamps. The second day after Diwali is considered auspicious for brothers and sisters. If the sister is married, the brother will go to her house and bring her to the father's home where she is dined and given gifts. The sister in turn will tie a thread on the brother's wrist, signifying that the brother will safe-guard the sister all the time. With that finish the Diwali celebrations.
Diwali commemorate the return of lord Rama to Ayodhya after 14 years.People welcomed him by lighting diyas and candles.
People light diyas on this day.
April
On Diwali-this indicates festival Diwali. At Diwali-It might indicates Diwali is some Place.
Diwali cards are sent to peple on diwali to wish them.
Diwali is a festival which is celebrated in India and Nepal. While it is particularly sacred to Hindus, practitioners of other Indian religions also celebrate Diwali, and Jainist, Hindu, and Sikh communities all over the world commemorate Diwali with smaller festivals of their own. The timing of this holiday varies, since it is based on the Hindu lunar calendar, but it is generally celebrated in the fall. Diwali festivities in India involve everyone, not just the religious faithful, and the holiday is a major event in the Indian year.The festival celebrates the triumph of good over evil. In Hindi, Diwali means "festival of lights," and people light rows of lights to commemorate heroic figures in Indian mythology who triumphed over the forces of evil. Diwali is also a propitious time for new endeavors, and many people clean their homes and open all their windows and doors to welcome luck and good fortune during Diwali. The exchange of gifts is also traditional during this holiday, and many people host dinners and Diwali parties.Regional traditions vary immensely when it comes to celebrating Diwali, because each community has developed its own unique way of celebrating this holiday. Technically, Diwali is five days long, with each day representing a different facet of the festival of lights. In many communities, people pick one day of Diwali in particular to celebrate, often with fireworks and other large public festivities.
Fire crackers are Diwali crackers. Being lighten up on diwali people also call them as Diwali crackers.
Diwali is spelled Diwali.
"Subho dipabali" means "Happy Diwali" in Bengali.
Diwali is a fun festival!
Yes candles are used in Diwali. Diyas are also lit on Diwali.
Commemorate
Diwali is one of the important festivals in India. It is the festival of light. "Happy Diwali" is a greeting one conveys to other on occasion of Diwali.
Diwali is not always celebrated in November the date of Diwali depends on the Hindu calender.
Diwali but it is pronounced DEE-VAHL-EE