Here is your short paragraph on Doljatra:
Doljatra is observed by the followers of the Vishnu cult in Bengal, most particularly in Nabadvip and Santipur and also in Orissa.
On Dol Purnima, in a swing the image of the Lord is placed gaily decorated and is then taken out in a procession.
This day also commemorates the birthday of Nimai/Gauranga/Chaitanya Mahaprabhu of Bengal and as such the day acquires a special significance for his devotees.
The most unique feature of Holi festival prevalent in Bengal is that a religious element is associated with it.
Swinging of Krishna image on Phalguna Full Moon is done in Bengal, but is not observed in several other parts of India.