Ember use local JSON file instead of Mirage provided in tutorial

I am new to building websites and all I want to do at this stage is to use local JSON file to retrive data instead of mirage provided in ember tutorial. you have mirage/config.js like this:

export default function() {
  this.namespace = '/api';

  let rentals = [{
        //JSON
      }];


  this.get('/rentals', function(db, request) {
    if(request.queryParams.area !== undefined) {
      let filteredRentals = rentals.filter(function(i) {
        return i.attributes.area.toLowerCase().indexOf(request.queryParams.area.toLowerCase()) !== -1;
      });
      return { data: filteredRentals };
    } else {
      return { data: rentals };
    }
  });

  // Find and return the provided rental from our rental list above
  this.get('/rentals/:id', function (db, request) {
    return { data: rentals.find((rental) => request.params.id === rental.id) };
      });
}

This article shows part of the solution but I don't know where it's supposed to be written. Any help would be much appreciated.