You want it slow....lets make it like its your first time......
Before partition, the Muslims make up 77% of Kashmir, and it is assumed that Maharaja Hari Singh would choose to join Pakistan because of this reason
During Partition, he changes his mind and decides to remain independent
Pakistan and its goons (mix of army and afghan tribesman) attack Kashmir to muscle Hari Singh into ascending to Pakistan
Hari Singh looks to India for help....India lays the condition that Kashmir would have to be integrated into India
Indian army arrives in Kashmir to cleanse it and frees 2/3 of Kashmir past which a cease fire is called
Pakistan and its army under assumptions of a being a "martially superior race" decide to launch operation Gibraltar and muscle Kashmir out of India.....unsuccessfully leading to the '65 war....
Realizing that taking Kashmir from India is not an option militarily, in the 1980's, Pakistan decides to send militants(Pakistani citizens from ***), train unemployed/fanatical/easily malleable Kashmiri youth to start an insurgency, and fight the state.....