title: Add separate component to Angular 2
body: <p>I have to add some component(comments for example) to my app:
  I'm trying:</p>
  
  <p>in comment.component.ts:</p>
  
  <pre><code>import { Component } from '@angular/core';
  
  @Component({
      selector: 'am-comments',
      template: `&lt;h4&gt;{{title}}&lt;/h4&gt;`
  })
  
  export class CommentComponent {
      title = 'Comments title';
  }
  </code></pre>
  
  <p>my app.module.ts:</p>
  
  <pre><code>import { NgModule }      from '@angular/core';
  import { BrowserModule } from '@angular/platform-browser';
  import { FormsModule }   from '@angular/forms';
  
  import { AppComponent }  from './app.component';
  import { CommentComponent } from './comment.component'; &lt;--
  
  @NgModule({
      imports: [
          BrowserModule,
          FormsModule
      ],
      declarations: [
          AppComponent,
          CommentComponent // &lt;--
      ],
      bootstrap: [ AppComponent ]
  })
  export class AppModule { }
  </code></pre>
  
  <p>finally in output :</p>
  
  <pre><code>&lt;am-comments&gt;Waiting...&lt;/am-comments&gt;
  </code></pre>
  
  <p>But it doesn't output template from CommentComponent outsite parent component</p>
  
  <p>What I've missed?</p>
  
  <p>Dir structure very simple:</p>
  
  <p><a href="https://i.stack.imgur.com/HDFEu.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/HDFEu.jpg" alt="enter image description here"></a></p>