how to read json file

[snippsat]

Use Code Tag,and there is no indentation in code you have posted.
There is mix of two diffent quotation marks in the json sample,that will never work.
"category”

but how does it match with my problem,i mean here i have very very complex data model like below:-

You struggle even with the most basic stuff as usage of OS,files...ect,have you looked into and learned some basic Python?
If this is task you have gotten,ask people who have given it you to help get started.