This code defines a WPF application with a main window class and a secondary page class. The main window class contains a button click handler that instantiates the secondary page class and sets it as the window's content when clicked. The secondary page class defines a grid layout for its XAML page.

1. using System;
using System.Collections.Generic;
using System.Windows;
namespace Del_Console_and_WPF
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
Page1 page1 = new Page1();
this.Content = page1;
}
}
}

2. <Page x:Class="Del_Console_and_WPF.Page1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:Del_Console_and_WPF"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800"
Title="Page1" x:Name="Page2nd">
<Grid Background="Lavender">
</Grid>
</Page>