Janmashtami is the celebration of the birth of Shri Krishna. Shri Krishna was born on the 8th day of Krishna Paksh in the month of Bhadon in Rohini nakshatra at midnight.
He was born in a prison in Mathura to Vaasudev and Mata Devaki. Shri Krishna was raised by Mata Yashoda and Nand Baba in Vrindavan. His older brother was Balram, an avtaar of Sheshnag.
Although the timing of Puja varies in Janmashtami, as the entire day is believed to be very auspicious, most people prefer to conduct Puja at mid-night. The general routine for the entire day goes like this:
Preparation for 
the PujaA small cradle decorated with flowers and a small potda (handkerchief is kept in the cradle)
New clothes for God’s idols
Panchamrit made out of unboiled milk, curds, ghee, honey and powdered sugar
Flowers and flower garlands, chandan, ittar
Puja Process: * Early in the morning, devotees give a bath to Lord Krishna, which is also termed as “abhishek”. The bathing ingredients comprise of the Gangajal, ghee, water, honey and curd.
* Once Bal-Gopal (Shri Krishna) is given bath, devotees embellish and beautify the idol of Krishna with newly purchased jewellary, accessories and clothes. Many devotees spend days before the Janmashtami to purchase these clothes and ornaments for Krishna.
* The idol of Krishna is then made to swing as a part of tradition.
* Bhog (an offering to lord), comprising of fruits, kheer, pedha etc… is offered to Lord.
* Along with all the above steps Krishna Aarti, mantras, bhajans are sung melodiously that fills the environment with positive vibrations.
Krishna AartiArti is one of the most important parts of any pooja process on any festival. Krishna arti is as follows. Is is considered to be very auspicious to play some kinds of musical instrument along with singing the arti.
Aaratii Yugala Kishora Kii Kiijai
Tana Mana Dhana Sab Arpana Kiijai
Ravi Shashi Koti Vadana Kii Shobhaa
Taahi Nirakha Meraa Mana Lobhaa
Gaura Shyaama Mukha Nikhrata Riijhai
Prabhu Ko Ruupa Nayana Bhara Pijai
Kanchanna Thaala Kapuura Kii Baatii
Hari Aaye Nirmala Bahii Chaatii
Phuulana Kii Seja Phuulana Kii Maalaa
Ratna Sinhaasana Baithe Nandalaalaa
Mora Mukuta Kara Muralii Sohai
Natavara Vesha Dekha Mana Mohai
Anga Niila Piita Pata Saarii
Kunja Bihaarii Giravaradhaarii
Shri Purushottama Girivara Dhaarii
Aaratii Karata Sakala Nar Naarii
Nanda Nandana Vrushahaanu Kishorii
Paramaananda Svaamii Avichala Jodii
Krishna Janamashtami Video