how to call my button component in my app-root component in "row-fluid div"

I have created a simple application in Angular8, and using some routing link and components.

on click on left Navigation I want call that component in my middle of the body as per attached screen shot.

My workings for:

**app-routing.module.ts**
import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

import { ButtonComponent } from './button/button.component';
import { CardsComponent } from './cards/cards.component';
import { PageNotFoundComponent } from './page-not-found/page-not-found.component';


const routes: Routes = [
  {path: 'button', component: ButtonComponent},
  {path: 'cards', component: CardsComponent},
  {path: '', redirectTo: '/button', pathMatch:'full'},
  {path: '**', component:PageNotFoundComponent}
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

I have written all my HTML code in app.compnent.html

**app.compnent.html**
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { ButtonComponent } from './button/button.component';
import { CardsComponent } from './cards/cards.component';
import { PageNotFoundComponent } from './page-not-found/page-not-found.component';

@NgModule({
  declarations: [
    AppComponent,
    ButtonComponent,
    CardsComponent,
    PageNotFoundComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }