To some extent, the life of an individual depends on the date and place of birth, his or her family background and also current location. So horoscopes which are based on the personal details of a person, can be fairly accurate for a large section of the population, as most people are leading fairly similar and predictable lives, especially if the astrologer is experienced and has interacted with a large number of people. A visitor to the website can order a 3 month transit chart after providing his or her personal details like date of birth, time of birth, place of birth, place where he or she is currently residing and exact period for which the transit chart is required.
Most people are able to handle pleasant or unpleasant situations far better if they were told about it well in advance, so that they can plan for it. While there is no guarantee that the 3 month transit chart will be completely accurate, the person who ordered it should treat it as a self help tool to improve their life.