Find out the date and time
First of all you need to determine the exact time and date of this festival. You need to have a Hindu calendar. It usually comes in the months of October and November. Diwali is celebrated after the Hindu month of Ashwauyuja ends.
In order to get the Hindu calendar or to figure out the dates you can visit Hindunet.org or simply search it in Google.com
Figure out the type of Diwali you want to celebrate
After finding out the dates, you need to check that which type of Diwali you want to enjoy. Diwali is celebrated by Sikhs, Hindus and Jains.
Dhanteras is the first day of Diwali which you can enjoy by simply shopping. You need to buy clothes, fireworks and all stuff which help you celebrate this festival.
Celebrate Naraka Chaturdasi
The second day of Diwali is known as Naraka Chaturdasi. In this day, first you need to wake up before sunrise and take bath. Then light you house with lamps and wear new clothes which you bought on the first day of Diwali.
You can also use fireworks and hang out with friends and families.
Third day or the main day of Diwali
In the third day, you have to enjoy to maximum. It is the main day of Diwali and takes place when new moon comes.
The fourth day of Diwali is known as Annakut in which you pray. It marks the day when Krishna defeated Indra. Thus it is an important and religious day for Hindus.
End celebration on Bhayi duj
On the last day of Diwali which is also known as Bhayi duj, you end the celebration. In this day, you spend time with you siblings and family members.