import { NgModule }       from '@angular/core';
import { BrowserModule }  from '@angular/platform-browser';
import { FormsModule }    from '@angular/forms'

import { AppComponent }   from './app.component';
import { HeroDetailComponent } from './hero-detail.component';
import { HeroesComponent }     from './heroes.component';
import { HeroService }         from './hero.service';


@NgModule({
  imports:      [ BrowserModule, FormsModule],
  declarations: [ AppComponent, HeroDetailComponent, HeroesComponent],
  bootstrap:    [ AppComponent ],
  providers:    [ HeroService ]
})
export class AppModule { }

import { NgModule }       from '@angular/core';
import { BrowserModule }  from '@angular/platform-browser';
import { FormsModule }    from '@angular/forms'
import { AppComponent }   from './app.component';
import { HeroDetailComponent } from './hero-detail.component';

@NgModule({
  imports:      [ BrowserModule, FormsModule],
  declarations: [ AppComponent, HeroDetailComponent, HeroesComponent],
  bootstrap:    [ AppComponent ]
})
export class AppModule { }

--- 
+++ 
@@ -1,12 +1,17 @@
 import { NgModule }       from '@angular/core';
 import { BrowserModule }  from '@angular/platform-browser';
 import { FormsModule }    from '@angular/forms'
+
 import { AppComponent }   from './app.component';
 import { HeroDetailComponent } from './hero-detail.component';
+import { HeroesComponent }     from './heroes.component';
+import { HeroService }         from './hero.service';
+
 
 @NgModule({
   imports:      [ BrowserModule, FormsModule],
   declarations: [ AppComponent, HeroDetailComponent, HeroesComponent],
-  bootstrap:    [ AppComponent ]
+  bootstrap:    [ AppComponent ],
+  providers:    [ HeroService ]
 })
 export class AppModule { }
Add the supporting import statements for AppComponent
