You can read about the story of Tripurasura in below Link http://hindumythologybynarin.blogspot.com/2014/04/tripurasur-three-demons-killed-by-lord.html
What to learn from story of tripurasur
How to kill tripurasuras who are present human body .
When tripurasur requested boon from Lord Brahma dev that they should be killed by only one arrow when 3 forts of golden, silver and bronze are in linear position which could be possible only 1000 divine years .
So similarly – Our body is made has 3 puras, just like thripurasur puras, with names
Sthula Shariram – Body which we see which has 5 Indhriyas (senses), eyes, mouth, skin, foot ,flesh . blood etc with 9 exits ( holes in body, eyes, ears, nostrils,mouth , excretory system )
Sukshma Shariram Means Mande of 5 Pancha Gyanaindhriyas mano budhi ,Chitha ahankara means
Mano – feelings in Heart – which gives us options in life.
Budhi – taughts in Mind – which helps in choosing the options.
Chithham – wish for something (Concentration and determination to do something ) – which makes us work to do which was decided by mind.
Pride ( ahankara ) – which forces you to take credit of everything which was done right and blame others for his mistakes.
This are the main duties for
Karana Shariram – apart from 9 holes mentioned and we know and discussed in Sthula shariram – there are believed to 2 more holes in human body one would be closed at birth which is the entry of the Jeeva into the body is umbilical cord, and other is brahma Randhra( Crown Point ) which would be exit .
In order to reach the God we need to break the 3 puras and then we can reach Lord Shiva
When we are able to get over these puras in our body which are Sthula, Sukshma , and Karana Sharira that state is called Moksha .
Opening the Exit door called Brahma Randhra should be only through yogic and Sadhana .
With Sthula , Sukshma and Karana shariras , we get 3 Avasthas ( State ) Jagruth, Swapna
Jagruth – keeps sthula Sharira alive – all the senses biological sense, pain everything is through jagruth ( awakening of the biological body ) . which we consider to be biologically alive or dead .
Swapna – which means dreams, in this state our sthula Sharira is inactive and our Jagruth is not active. Swapna is controlled by Sukshma Sharira where most of the creations in this materialistic world happen, anything to be created or innovated one is initiated in this state . few people carry them with Sthula sharira along with Sukshma Sharira and say it as achieving of dreams .
Sushukthi – is the state of the body which generates happiness and sadness, loneliness etc. due to the actions of Jagruth and Swapna .
When we are able to win all these 3 states Jagruth, Swapna, and Sushukti Avastas then we are in avastha of vyragya which leads to moksha,
Vyragya Avastha is not Being Sad infact being happy irrespective of Actions, Reactions and incidents happening infront of Sthula, sukshma and Karana Shariram
Vyragya avastha is a state of happiness of Realising reaching and connecting of god in your human body to the god who exist in every living being . connection of god who is created world which we see through 3 Shariras and feel through 3 Avasthas.
3 Avasthas ( Jagruth, Swapna , Sushukthi ) Can be compared to ( Preserver(Sthithi), Creation(Srushti), Laya ( Destruction ) . Due to this world what we see exits. One who can go beyond these is called Yogi. They are the ones who reach god , they are someone who can really open their Brahma Randhra( Crown hole ) and who can understand what is the reality beyond the world what we see through 3 shariras, 3 avasthas and 3 Karmas ( Acts)
Person who can over come these 3 sharira, 3 avasthas, 3 Karmas is tripurari , and who can help us in this is that Lord Shiva as Tripuranthaka.