Помогите, пожалуйста, написать приложение для Windows Forms на C#

 namespace WinFormsApp1 
{ 
    public partial class Form1 : Form 
    { 
        public Form1() 
        { 
            InitializeComponent(); 
            comboBox1.Items.AddRange([new Converter("kg", 1), new Converter("mg", 1e-6), new Converter("g", 1e-3), new Converter("t", 1000)]); 
        } 
 
        private void textBox1_TextChanged(object sender, EventArgs e) 
        { 
            try 
            { 
                double d = double.Parse(textBox1.Text); 
                textBox2.Text = ((Converter)comboBox1.SelectedItem)[d].ToString(); 
            } 
            catch 
            { 
                textBox2.Text = string.Empty; 
            } 
        } 
    } 
 
    public class Converter 
    { 
        private double ConversionFactor = 1; 
        private string UnitName; 
        public Converter(string _UnitName, double _ConversionFactor) 
        { 
            UnitName = _UnitName; 
            ConversionFactor = _ConversionFactor; 
        } 
 
        public override string ToString() 
        { 
            return UnitName; 
        } 
 
        public double this[double _Value] { get => _Value * ConversionFactor; } 
    } 
}