Here is your short paragraph on Kartik Purnmasi:
A dip in the Ganges on Kartik Purnmasi is believed to be the holiest and there are big congregations in Uttar-Pradesh, particularly at Garhmukteshwar, Soran Rajghat, Kakora, Bithur, Kanpur, Allahabad, Varanasi, Ayodhya and Haridwar.
Each year at Kartik full moon, the Goddess Tulsi is married to Vishnu. The Tulsi is a small tree devoted to God Vishnu both a plant and
Goddess.Traditionally each Hindu family is supposed to own a branch planted in a stone worked square in the middle of the courtyard and ladies worship it daily. Worshippers of Vishnu adorn themselves with Tulasi leaves and wear a necklace made out of its wood.
On Kartik Purnima, in Tamil Nadu there is a custom of burning dry leaves of the palmyra, knitted together in heaps, and burnt which goes by the name of Chokkappanai in front of the temples on the occasion, perhaps to represent Lord Siva burning three fortresses (viz., Tiripuram).
The Lord is offered a preparation of fried rice mixed with jaggery on this holyday. The day is observed with full religious fervour in the Arunacalesvara Temple at Tiruvannamalai and tens of thousands throng there to witness this nine days celebration. On Kartik Purnima day, all houses in South India are illuminated at sunset with lights in hollow earthen lamps.