How clicking barItem in Navigation Bar will bring new content page - xamarin.forms

Question

[![enter image description here][1]][1]This is the MainPage which has a navigation Bar that contains 4 barItems.
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
Title="CheckList"
x:Class="mmy.View.MainPage">
<ContentPage.ToolbarItems>
<ToolbarItem Name="MenuItem1" Order="Primary" Icon="itemIcon1.png" Priority="0" />
<ToolbarItem Name="MenuItem2" Order="Primary" Icon="itemIcon2.png" Priority="1" />
<ToolbarItem Name="MenuItem1" Order="Primary" Icon="itemIcon3.png" Priority="2" />
<ToolbarItem Name="MenuItem2" Order="Primary" Icon="itemIcon4.png" Priority="3" />
</ContentPage.ToolbarItems>
<ContentPage.Content>
<StackLayout Orientation="Vertical">
<Label Text="MainPage"/>
</StackLayout>
</ContentPage.Content>
</ContentPage>
The Navigation Bar will look like below:
-------------------------------------------------------
Main barItem1 | barItem2 | barItem3 | barItem4
-------------------------------------------------------
Item1_Content
Say , I have 4 bar items in the Navigation bar
I want to do the following:
When user click barItem2 ,
a) it will bring in a Item2_Content which will replace the Item1_Content. ( I m not sure there is such UI )
b) the barItem (1 to 4 ) still remain in the navigation bar.
Is this doable?
Can you help me how to implement such user requirement?
Thanks
Update:
--(1) - start at P1 :
private async void BtnLogin_Clicked(object sender, EventArgs e)
{
NavigationPage NP = new NavigationPage(new MainPage())
{
BarBackgroundColor = Color.White,
BarTextColor = Color.DarkGray
};
}
--(2) I created a new page call RepairSvc for (3)
--(3) At MainPage : it has a navigation bar from (1)
Click the Icon="itemIcon1.png"
<ToolbarItem Name="MenuItem1" Order="Primary" Icon="itemIcon1.png" Command="Item1Command" Priority="0" />
Code Behind :
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MainPage : ContentPage
{
public ICommand Item1Command { get; private set; }
public MainPage()
{
InitializeComponent();
this.Item1Command = new Command((sender) =>
{
Navigation.PushAsync(new RepairSvc());
});
}
}

Answer 1

assign a command to your toolbar
<ToolbarItem Name="MenuItem1" Order="Primary" Icon="itemIcon1.png" Priority="0" Command="Item1Command" />
in your codebehind
this.Item1Command = new Command((sender) =>
{
Navigation.PushAsync(new MyPage());
});
}
public ICommand Item1Command { get; private set; }