C#

Drag a Button on to the Designer.  See how it updates the Xaml with the Button tag.  Selecting items in the Document Outline Window allows you to navigate the Xaml tree and it selects the item visually as well as in the Xaml.  It is a handy way to navigate complex Xaml if not all of the Xaml is visable.
 Select the Button go to the properties Window - this also creates events.
You can edit the control in the Properties Window or hand-edit the Xaml. To create an event you can either use the properties window or edit the Xaml.
To do this go to the Xaml for MainPage.xaml and find the Button that was added.  Type Click= and then tab to create the event handler.  This has been added in the code-behind .cs file.  Type Button1.Content = "Hello World!"

I have done what it has say and my MainPage.xaml.cs looks like this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;

namespace Hello_World
{
    public partial class MainPage : PhoneApplicationPage
    {
        // Constructor
        public MainPage()
        {
            InitializeComponent();
        }

        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            Button.Content = "Hello World";
        }
    }
}


the 'Button.Content' produces this error:

Error	1	An object reference is required for the non-static field, method, or property 

My MainPaipe.zaml has the following code in but no errors

<phone:phoneapplicationpage 
="" x:class="Hello_World.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone" xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:ignorable="d" d:designwidth="480" d:designheight="768" fontfamily="{StaticResource PhoneFontFamilyNormal}" fontsize="{StaticResource PhoneFontSizeNormal}" foreground="{StaticResource PhoneForegroundBrush}" supportedorientations="Portrait" orientation="Portrait" shell:systemtray.isvisible="True">

    
    <grid x:name="LayoutRoot" background="Transparent">
        <grid.rowdefinitions>
            <rowdefinition height="Auto">
            <rowdefinition height="*">
        

        
        <stackpanel x:name="TitlePanel" grid.row="0" margin="12,17,0,28">
            <textblock x:name="ApplicationTitle" text="MY APPLICATION" style="{StaticResource PhoneTextNormalStyle}">
            <textblock x:name="PageTitle" text="page name" margin="9,-7,0,0" style="{StaticResource PhoneTextTitle1Style}">
        

        
        <grid x:name="ContentPanel" grid.row="1" margin="12,0,12,0">
            <Button Content="Button" HorizontalAlignment="Left" Height="79" Margin="142,53,0,0" VerticalAlignment="Top" Width="171" Click="Button_Click_1"/>
        
    
 


Help Appreiated

Paddy