Lord Vishnu is one of the lord of the Hindu Trinity apart from Lord Brahma and Lord Shiva.
Sri Krishna is the incarnation of Lord Vishnu. Sri Krishna was born in Dvapara age. Lord Krishna was born in prison Maa Devaki and Vasudeva. He was raised by his foster parents Nanda and Yasoda in Gokul. Lord Krishna is the destroyer of evil and he vanquished demons Trinavarta and Putana.
Lord Krishna puja is done to get his blessings. This puja is done for various fulfilments of wishes. People get it performed for love, happiness, career, finance, business, health and for various other desires. Lord Krishna is worshiped and prayed from the heart.
You too can get the Lord Krishna puja done. This puja is done any day but especially on Janamasthmi this puja has great effects.