Oprion 1:

If you can add an anchor tag that will be simplest.

<a routerLink="/addposts" routerLinkActive="active">Add Post</a>

Option 2:

Follow these 3 simple steps.

Step 1: Import the angular router

import { Router } from '@angular/router';

Step 2: Inject the value using dependency injection

constructor(
      private router:Router,
      ...
)

Step 3: Invoke the navigate() inside your click event

this.router.navigate(['/addposts']);

I am assuming you want to navigate to a different page because you want to route to post/addposts. Then you can just change your path to this

{ path: 'post/addposts',component:AddPostComponent}];

I might be wrong and you might want to use multiple router-outlet instead.

first install router via: npm install router

import { Routes, RouterModule } from '@angular/router';


export const router: Routes = [
   { path: '',  redirectTo: 'main', pathMatch: 'full'},
  { path: 'main', component:AdminBodyComponent  },
  { path: 'admin', component:AdminComponent  },
  { path: 'posts',component:PostsComponent},
  { path: 'addposts',component:AddPostComponent}];

export const routes: ModuleWithProviders = RouterModule.forRoot(router);
step2:
inject into your .ts file
constructor(
  private router:Router,
  ...
)
step3:
this.router.navigate(['/addposts']);

step4:
<base href="/">

if you want to use specific router go for this step4: