Yajña is a performance to create a strong link between the individual in physical life and an aspect if the individual in the celestial realm for the purpose of living in greater accord with the Universe. Yajñas are highly scientific and precise multi-dimensional esoteric techniques to invoke and direct the transcendental cosmic energy into concrete, tangible and constructive fruits. In Brahman Consciousness, one lives in perfect harmony with the Universe. Every individual that is in physical form is attached to a package of karma that defines the life experience. When this package of karma is balanced, then one can live in perfect harmony with the Universe.
“Ayam Yajño Vishwasya Bhuvanasya nabhihi” (Atharva Veda 9/15/14). It means Yajñas are the central focus of the Universe. When Lord Brahma created the Universe, He created Yajña to fulfill material and spiritual needs.
Almost every act from ego volition results in unbalanced karma. Unbalanced karma is a potential for reaction or a seed for action, waiting for the opportune moment to express itself and thereby become balanced. Unbalanced karma accumulates from life to life with only a small part getting balanced in a particular life and usually more new unbalanced karma is generated in every life until there are "mountain ranges" of unbalanced karma associated with most individuals.
To balance the karma for this life, there are a total of 12 SriVyuha Jyotish Yajñas that you can perform. Here is a list of the complete yajña kits. Each kit contains everything you need to perform the yajña for the Graha (instructions, full-color composite yantra for the Graha with your personal yantra, and audio recording of the invocation of Ganesh and the Graha Mantra), except for the statue of Ganesh, mala and ghee lamp and ghee or ghee candles. You will need one small statue of Ganesh, and one crystal mala of 108 beads to count repetitions. Also you will need either a ghee lamp, wicks and ghee or ghee candles and a holder. You will have to print the yantra in color and frame it in a gold frame. If you have the time and resources, you may want to keep the ghee lamp or ghee candle burning 24x7 throughout the time of the yajña, or you can just burn the lamp during the performance.