why the puja is structured in a certain way.

let us see why the puja is structured in a certain way.
Let us think of a guest visiting us. He is a very respectable person. What we do first?
We welcome him. In the villages such a person will be taken in made to sit and water is to offered wash the feet and drink. Once he is refreshed . He bathes , depending on the weather and his physical condition in hot water or cool water from the well. Then he is given clothes to wear. While the food is getting ready we chat something that is warm to the heart. Then we eat. After that comes beetle leaves and areca nut. It is customary to offer dhakshina to one who has taken the food. Since this person is an elder of repute we prostrate before him and receive his blessings. When he wants to take leave we arrange a vehicle for him.
Now look at the puja. We think of God being in a particular picture or stone. That is Dyanam. We request Him to be in it till the puja is over. This is avahanam. Then we offer a seat – asanam. We pour water in his feet and hands- patha prakshalanam and argyam. Asamanam is offering water to drink. Then the bath. Samanam again. Wearing the sacreed thread and dress. Wearing the jewels. Arcana with flowers; showing the doopa and ghee lamp. Offering the food that has been prepared with love and care- nivedanam. Showing the burning camphor in front of him. Saying his praise by verses. Offering a golden flower. Circumnavigating and prostrating at his feet. Showing the mirror to him. Letting him ride an elephant or chariot. Finally submitting all the effects from puja acts to Him. Such a puja is called shodopasara puja.