Horoscope or Jataka Chakram is a chart or map of the positions of the Sun, Moon and Planets as they appear over a certain place at the time of birth. Based on the cycles and the movement of the planets it is possible to find how they will be positioned at any given specific time in your lifetime. From this, the astrologer can tell you what possible effects these planets could have on you during your life time.
You have to join astrology classes to learn it properly. However there are free internet softwares which can make it for you...one is... www.10001downloads.com/s/jathaka-chakram.html
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First of all One should have date, time and place of birth to proceed to draw a jataka chakram with the help of ephimeries which give you the information regarding thithi,star,sunrise,sunset, lagne at the time of birth and also we have to calculate side real time and other things to finally get a chart.