Løkker og arrays

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        int[] kunder = new int[10];
        public Form1()
        {
            InitializeComponent();
        }

        private void btnOpdater_Click(object sender, EventArgs e)
        {
            int kundenr = int.Parse(txtKonto.Text);
            int saldo = int.Parse(txtSaldo.Text);

            kunder[kundenr] = saldo;
        }

        private void btnTotal_Click(object sender, EventArgs e)
        {
            int total = 0;
            for (int i = 0; i < 10; i++)
            {
                total = total + kunder[i];
            }
            lblTotal.Text = total.ToString();
        }
    }
}