Hi @dariyaamrut, Welcome to the Community 
I have moved your topic to āGeneral Discussionā from āfrom the expertsā category 
since this is appropriate.
To answer to your question,
Can you please provide little more information for us to help better. Kindly read this post.
Okay I get that you are trying to do a end-to-end testing, integrating your front end and backend.
Postman is API management tool, where as you can create, tests and document you APIās. Does your application use APIās for communicating? If so, do you have the API documentation or any sort of collections available already to start off? Please provide more details on your requirement 