how to insert,update,delete rows from sql server tables

sir i m using below technique to connect the databade but now i m unable to add ,update any record please help me

http://www.homeandlearn.co.uk/csharp/csharp_s12p1.html

database name is mydb

it contian 1 table namw INFO fields are

id(primry key auto increament 1 ,) ,Name , Lname , job 

i made a class name in Data

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace WindowsFormsApplication5
{
    class DatabaseConnection
    {
        private string sql_string;
        private string strCon;
        System.Data.SqlClient.SqlDataAdapter da_1;


        public string Sql
        {
            set { sql_string = value; }
        }


        public string connection_string
        {
            set { strCon = value; }
        }


        public System.Data.DataSet GetConnection
        {

            get { return MyDataSet(); }

        }

and my form data is 

n

amespace WindowsFormsApplication5
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        DatabaseConnection objCon1;
        string conSt1;
        DataSet ds1;
        DataRow dRow1;
        SqlConnection con;

        private void Form1_Load(object sender, EventArgs e)
        {
            objCon1 = new DatabaseConnection();
            conSt1 = Properties.Settings.Default.mydbConnectionString;
            objCon1.connection_string = conSt1;
            objCon1.Sql = Properties.Settings.Default.SQL;
            ds1 = objCon1.GetConnection;
            NavigateRecords();
        }
        private void NavigateRecords()
        {
            dRow1 = ds1.Tables[0].Rows[1];
            textBox1.Text = dRow1.ItemArray.GetValue(1).ToString();
            textBox2.Text = dRow1.ItemArray.GetValue(2).ToString();
            textBox3.Text = dRow1.ItemArray.GetValue(3).ToString();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            DataRow row = ds1.Tables[0].NewRow();
            row[1] = textBox1.Text;
            row[2] = textBox2.Text;
            row[3] = textBox3.Text;
            ds1.Tables[0].Rows.Add(row);
            objCon1.UpdateDatabase(ds1);


            MessageBox.Show("Database updated");



        }
    }

}