Newbie here - a few questions..

[Even92LN]

Thanks for your replies! Will look futher into it tomorrow. Btw, here's what my file looks like now:

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

namespace WindowsFormsApplication5
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void label2_Click(object sender, EventArgs e)
        {

        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void label3_Click(object sender, EventArgs e)
        {

        }

        private void label5_Click(object sender, EventArgs e)
        {

        }

        private void label6_Click(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            {
                if (textBox2.Text == "")
                {
                    MessageBox.Show("Only numbers allowed");
                }
                int dist = int.Parse(textBox1.Text);
                int cAlt = int.Parse(textBox2.Text);
                int tAlt = int.Parse(textBox3.Text);
                int spd = int.Parse(textBox4.Text);
                int vs;
                vs = -((cAlt - tAlt) * spd) / (dist * 60);

                textBox5.Text = vs.ToString();
            }
        }
        

        private void textBox2_TextChanged(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {
            textBox1.Text = "";
            textBox2.Text = "";
            textBox3.Text = "";
            textBox4.Text = "";
            textBox5.Text = "";

        }

        private void textBox5_TextChanged(object sender, EventArgs e)
        {

            textBox5.ReadOnly = true;

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            
        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox4_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            { //accept only numbers and back space.
                if ((e.KeyChar < '0' || e.KeyChar > '9') && (e.KeyChar != '\b'))
                {
                    MessageBox.Show("Only numbers allowed");
                    e.Handled = true;
                }
                else
                {
                    e.Handled = false;
                }

            } 

            }

        private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
        {
            { //accept only numbers and back space.
                if ((e.KeyChar < '0' || e.KeyChar > '9') && (e.KeyChar != '\b'))
                {
                    MessageBox.Show("Only numbers allowed");
                    e.Handled = true;
                }
                else
                {
                    e.Handled = false;
                }

            } 
        }

        private void textBox3_KeyPress(object sender, KeyPressEventArgs e)
        {
            { //accept only numbers and back space.
                if ((e.KeyChar < '0' || e.KeyChar > '9') && (e.KeyChar != '\b'))
                {
                    MessageBox.Show("Only numbers allowed");
                    e.Handled = true;
                }
                else
                {
                    e.Handled = false;
                }

            } 
        }

        private void textBox4_KeyPress(object sender, KeyPressEventArgs e)
        {
            { //accept only numbers and back space.
                if ((e.KeyChar < '0' || e.KeyChar > '9') && (e.KeyChar != '\b'))
                {
                    MessageBox.Show("Only numbers allowed");
                    e.Handled = true;
                }
                else
                {
                    e.Handled = false;
                }

            } 
        }

        private void chart1_Click(object sender, EventArgs e)
        {

        }

        private void toolTip1_Popup(object sender, PopupEventArgs e)
        {
            

        }

        private void label11_Click(object sender, EventArgs e)
        {

        }

        private void toolTip1_Popup_1(object sender, PopupEventArgs e)
        {
            ToolTip toolTip1 = new ToolTip();
            toolTip1.ShowAlways = true;
            toolTip1.SetToolTip(textBox1, "Click me to execute.");

        }

        private void toolTip1_Draw(object sender, DrawToolTipEventArgs e)
        {

        }

        private void label12_Click(object sender, EventArgs e)
        {

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void toolTip1_Popup_2(object sender, PopupEventArgs e)
        {

        }
        }
    }