App.cs

using Xamarin.Forms;

namespace AppForms
{
    public class App : Application
    {
        public App()
        {
            MainPage = new ContentPage
            {
                Content = new StackLayout
                {
                    VerticalOptions = LayoutOptions.Center,
                    Children =
                    {
                        new Label
                        {
                            HorizontalTextAlignment = TextAlignment.Center,
                            Text = "Hola mundo desde Xamarin Forms!",
                            FontSize = 30
                        }
                    }
                }
            };
        }
    }
}