The adhana means placing. In adhanakarma, the sacred fire that is to be used for performing a srautakarma is generated and placed in the kundas. (These are pits suitable sizes and shapes constructed for growing or developing the sacred fires and also preserving them. This process is technically referred to as agnisiddhi, and it is carried out as follows.
Initially, the vedi (altar) is constructed at an appropriate place. Then the three sacred pits for placing the three fires, tretagni, are constructed as per the rules laid down in Sulba Sutras. Then by churning the firewood called arani, the sacred fire to be used for srauta karma is generated. This fire is first placed in the sacred pit constructed for garhapatyagni by the priest called adhvaryu. This process is known as grahapatyadhanam.
This grahapatyagni is grown up by adding ghee, firewood, etc., and then a part of it is transferred to the other two sacred fire pits for ahavaniyagni and dakshinagni. The process of hota, carrying the fire from the altar meant for grihapatyagni and placing it in the kunda meant for ahavaniyagni, is called ahavaniyadhanam. The process of agnidhra, carrying the fire and placing it in the basin meant for dashinagni, is called dashinagnyadhanam. In accomplishing this adhana karma, the yajamana (performer) takes the help of four priests, namely, adhvaryu, agnidhra, hotr and Brahman.