how to replace fragment by click on tabbed or BottomNavigationView item in xamarin.android

Question

[Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
public class MainActivity : AppCompatActivity, BottomNavigationView.IOnNavigationItemSelectedListener
{

protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.activity_main);
BottomNavigationView navigation = FindViewById<BottomNavigationView>(Resource.Id.navigation);

navigation.SetOnNavigationItemSelectedListener(this);
}
public bool OnNavigationItemSelected(IMenuItem item)
{
switch (item.ItemId)
{
case Resource.Id.navigation_home:

return true;
case Resource.Id.navigation_dashboard:

return true;
case Resource.Id.navigation_notifications:

return true;
}

return true;
}

}
}