Sri Krishna Janmastami marks the appearance day of Lord Vishnu incarnated as Krishna on this earth, to protect and reestablish Dharma. Lord Krishna was born in Gokul on the ashtami tithi, Krishna Paksha (eighth tithi after the full moon), of the Shravan or Savan month on the Vedic calendar, over 5,500 years ago during the last portion of dwapara-yuga. The Krishna avatar is the most holy of all avatars, a prem avatar, meaning all avatars combined into one. All the wishes of devotees in previous Avatars were granted by Krishna in this form. Lord Krishna was born at midnight in the prison of his maternal uncle Kamsa where his birth parents Devaki and Vasudeva were held. In 2015, the there are two dates for Janmastami, depending on your location on the planet. Devotees in Asia, Australia, Africa, the middle east, and Europe will celebrate on September 5th, 2015. Devotees in North & South America will celebrate on September 4th, 2015, as the ashtami tithi will be over by midnight on the 9th. The birth of the Lord is celebrated at midnight, but prayers should be done in the morning as well. On the day of Janmastami wake up before sunrise, start by taking a shower, and then prepare Prasadam for the Lord, along with fruits. It is preferred that the Prasadam be made of milk if being offered to Krishna, for example kheer (rice pudding), or makhan (butter). Make sure your altar is clean, clean the idol of Lord Krishna and offer rice unto his feet, light a diya (lamp) made of cotton and ghee (unsalted butter), as the akhand jyot, and have another one for Aarti. Prepare panchamritam (consists of milk, yogurt (no gelatin), honey, sugar (preferably brown), and ghee). Sprinkle water in and around your home or temple altar to purify the area. Acknowledge the presence of the devas who come to earth this time of the year to witness the Lord's birth ceremonies. Put the murti of Krishna in a plate and shower him with three spoons of the panchamritam prepared. Then clean him with three spoons of water, and add the liquid back to the rest of the panchamritam. Place Krishna back to his stationary spot in your altar. Touch the feet of Krishna, apply chandan, sindoor, and haldi to his feet, then to his forehead. Next take the Prasadam you have prepared and offer it to his feet, add Tulsi leaves to the Prasad if possible, then sprinkle water three times upon it. Lastly decorate the Lord with flowers, or even clothes. There are special mantras for offering tilak, prasad, tulsi, panchamrit and flowers, but if you do not know these mantras you can simply chant Om Namo Bhagavate Vasudevaya or Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare/Hare Rama, Hare Rama, Rama Rama, Hare Hare. You should also observe a fast if possible (don't kill yourself, do what you can), the preferred fast in Nirjala vrat, no food or water until midnight, but you can do a jala vrat (only water) or a phal vrat (only fruits and water as well. Chant all day, stay holy on this auspicious day, do not bash anyone. Near the evening come then gather to celebrate the birth of the Lord, before midnight, you can do a Yagya if you so desire, but stay joyful start at 10 PM and chant until midnight! 12 AM is the climax of the celebrations, this is when the Jhulan ceremony of the Lord should happen, put a picture/idol of Krishna in a swing and swing the Lord. After the Jhulan ceremony Aarti should be preformed, and then you can break your fast by eating Prasadam, and then sprinkle water on yourself to calm yourself down, do shanti paath. Many different cultures do this differently, but if you are unaware of your cultural practices, this is the standard way.