XAML:

<Page
    x:Class="UWPCourseApp2022.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:UWPCourseApp2022"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <StackPanel>
        <Button Margin="20" Click="Button_Click">Tässä on testipainike</Button>

        <TextBlock Width="428" HorizontalAlignment="Left" Margin="20" FontSize="30" Foreground="CornflowerBlue">Tervetuloa ohjelman käyttäjäksi!</TextBlock>

        <TextBox Name="UserText" Margin="20"></TextBox>

        <ComboBox Margin="20" Width="200">
            <ComboBoxItem>Banaani</ComboBoxItem>
            <ComboBoxItem>Omena</ComboBoxItem>
            <ComboBoxItem>Mansikka</ComboBoxItem>
            <ComboBoxItem>Hunajavesimeloni</ComboBoxItem>
        </ComboBox>

    </StackPanel>
</Page>

C#:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409

namespace UWPCourseApp2022
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            String txt = UserText.Text;
            Debug.WriteLine("Nappia on painettu!");
            Debug.WriteLine("Tervetuloa, " + txt);
        }
    }
}