Example of Local Notification in Xamarin.Forms applications - http://julianocustodio.com/local-notification

MainPage.xaml.cs

using System;
using Plugin.LocalNotifications;
using Xamarin.Forms;

namespace LocalNotificationDemo
{
	public partial class MainPage : ContentPage
	{
            public MainPage()
            {
		InitializeComponent();
	    }

	    public void Start_Notification(object sender, EventArgs e)
	    {
	        CrossLocalNotifications.Current.Show("Title","Text");
	    }

       }
}