Normally rangoli will be made in the festival of Diwali in India but it will not wait for any occassion. You can light up and decorate your place with this any time when you want to celebrate or you are very happy.
It is designed in many ways and can use any thing to decorate it. You will find many styles on you tube and decorate with flowers, colours, diyas etc.
You will find a lot of beautiful styles of rangoli on internet and it is very easy to decorate and make it with anything you want.