Programowanie textboxa

Witam. Mam pytanie. Probuje oprogramowac textboxy tak, zeby po przeskoczeniu do kolejnego wykonywalo instrukcje. Jak to zrobic? Probowalem cos z KeyUp ale nie do konca wiem jak to dziala.

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 For_homework
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            
            var LoopResult = new List<int>();
            var LoopParameters = new List<int>();
            LoopParameters = TakeInput();
            LoopResult = Looping(LoopParameters);
            Result(LoopResult);
            FinalResult(LoopResult);
        }
        private List<int> TakeInput()
        {
            var Loop = new List<int>();
            Loop.Add(int.Parse(textBox1.Text));
            Loop.Add(int.Parse(textBox2.Text));
            Loop.Add(int.Parse(textBox3.Text));
            Loop.Add(int.Parse(textBox4.Text));
            Loop.Add(int.Parse(textBox5.Text));
            Loop.Add(int.Parse(textBox6.Text));
            return Loop;
        }//Take the input
        private List<int> Looping(List<int> LoopParam)
        {
            var LoopSum = new List<int>();
            LoopSum.Add(0);
            LoopSum.Add(0);
            for (int i = LoopParam[0]; i <= LoopParam[1]; i += LoopParam[2])
            {
                LoopSum[0]+=i;
            }
            for(int i = LoopParam[3]; i <= LoopParam[4]; i += LoopParam[5])
            {
                LoopSum[1]+=i;
            }
            return LoopSum;
        }//Do the loop and summarize
        void Result (List<int> LoopResult)
        {
            resultA.Text = ""+LoopResult[0];
            resultB.Text = ""+LoopResult[1];
        }//Give result
        void FinalResult(List<int> LoopResult)
        {
            if(LoopResult[0]>LoopResult[1])
            {
                WhoWins.Text = "Player A wins";
            }
            else if(LoopResult[1]>LoopResult[0])
            {
                WhoWins.Text = "Player B wins";
            }
            else
            {
                WhoWins.Text = "It's a draw";
            }
        }//Give final result
        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            int i = int.Parse(textBox1.Text);
            if (i < 1 || i > 6)
                label3.Text = "Wrong number";
        }//Texbox evaluation

        private void textBox2_TextChanged(object sender, EventArgs e)
        {
            int i = int.Parse(textBox2.Text);
            if (i < 7 || i > 18)
                label4.Text = "Wrong number";
        }

        private void textBox4_TextChanged(object sender, EventArgs e)
        {
            int i = int.Parse(textBox4.Text);
            if (i < 1 || i > 6)
                label7.Text = "Wrong number";
        }//Textbox evaluation

        private void textBox5_TextChanged(object sender, EventArgs e)
        {
            int i = int.Parse(textBox5.Text);
            if (i < 7 || i > 18)
                label8.Text = "Wrong number";
        }
    }
}