TabbedPage hiding when pushing new Pages

Hi, I am developing Tabs in my application. When I am starting FirstPage from Tab1, It is hiding all the Tab's and showing page in full screen. How can I get Tabs in all screens of the app.
My code

  <?xml version="1.0" encoding="utf-8" ?>
    <TabbedPage  xmlns="http://xamarin.com/schemas/2014/forms"
                 xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                 x:Class="TabbedApp.MainPage"
                 xmlns:local="clr-namespace:TabbedApp">
        <local:DairyTabs></local:DairyTabs>
        <ContentPage Title="Tab 2">
            <StackLayout>
                <Label Text="Tab 2"   
                HorizontalTextAlignment="Center"  
                HorizontalOptions="FillAndExpand"  
                Margin="5" />
            </StackLayout>
        </ContentPage>
   </TabbedPage>

Code for starting Page2

btnDemo.Clicked +=async delegate {
                await Navigation.PushModalAsync(new Page2());
            };

See below images for more clarification