1. Import the HttpClient module in your app.module.ts file :

import { HttpClientModule } from '@angular/common/http';

@NgModule({
  imports: [
    HttpClientModule
  ]
})
export class AppModule { }

2. Inject the HttpClient module in the component you want to use it in :

import { HttpClient } from '@angular/common/http';

export class MyComponent {
  constructor(private http: HttpClient) { }
}

3. Use the HttpClient module to make a GET request to retrieve the JSON data:

import { HttpClient } from '@angular/common/http';

export class MyComponent {
  data: any;
  
  constructor(private http: HttpClient) {
    this.http.get('path/to/data.json').subscribe(data => {
      this.data = data;
    });
  }
}

4. Use the data in your component's template and class to display or manipulate it :

<div *ngFor="let item of data">
  {{ item.name }}
</div>

5. Alternatively, you can use the HttpClient to make POST, PUT and DELETE request to update your Json files.