Here is your short Paragraph on Manasa Puja:
This puja is mainly confined to Bengal and parts of Bihar, Orissa and Assam. Manasa is the goddess of snakes and like the snake (naga) cults of South India, Manasa cult was initially limited to the Unbrahmanised hill and jungle tribes, but today she is worshipped in every Bengal house-hold.
In India, there is no single instance of a snake-goddess who is herself not a snake, except that of Manasa in Bengal.
There is a myth that Siva had partially swallowen poison which emerged from the churning of the ocean (samudramanthana) added a sequel in which Manasa extracted the poison from his throat. Having fulfilled the role of remover of poison (Visahari), she distributed it among various snakes and insects, so accounting for the origin of the poisonous varieties and hence her supplementary epithet Visadhari, ‘controller of poison’.
The shrines of Indian snake-cult are to be found in many parts of India, particularly in the East (Assam and Bengal) and in the South. In Assam and Bengal, the snake-cult rites may vary from village to village, but the devotees are generally united in their worship of the goddess Manasa (Visahari), the ruler of serpents.
Earlier, snakes themselves were the objects of worship, whereas Mother Manasa herself is the goddess who is now worshipped and invoked for protection against them (being their leader and controller).
Interestingly, the Manasa cult also found among some Bengali Muslim communities. She is identified with the goddess Janguli by some Mahayana Buddhist. Padmavati, the female messenger (sasanadevata) of the twenty-third Jaina tirthankara, Parsvanatha, is perhaps the counter part of Manasa who is also called Padmavati.
On the fifth in Ashad/Sravana is marked out for the worship of the serpent goddess Manasa and the eight nagas. In Assam, worship of Manasa is called ‘Mare—puja’ and is observed by the Pati Rabhas with usual rites with the dancing and singing of the oja—pali and the deodhani.