How to use database using CLASS in asp.net

How to use database using CLASS in asp.net 

website -> add new item -> select class ( Apply code )

public class Class1
{
    SqlDataReader dr;
    SqlCommand cm;
    SqlConnection cn;
public string Connection()
{
       
        string cs = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True";
        return cs;
  }
    public string querry()
    {
        string k = "select * from Table1";
        return k;
    }
    public string INSERT()
    {

        string q = "insert into Table1 values";
        return q;
    }

}



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create aspx  page and  apply  code 

public void LoadGridview()
    {
        Class1 my = new Class1();
        string cs = my.Connection();
       
        cn = new SqlConnection(cs);
        cn.Open();
        string k= my.querry();

        cm = new SqlCommand(k, cn);
        dr = cm.ExecuteReader();

        GridView1.DataSource = dr;
        GridView1.DataBind();


    }
    protected void Button1_Click(object sender, EventArgs e)
    {
       
        Class1 MY1 = new Class1();
        string cs = MY1.Connection();
        cn = new SqlConnection(cs);
        cn.Open();
        string k = MY1.INSERT()+"('" + TextBox1.Text + "','" + TextBox2.Text + "','" + TextBox3.Text + "')";;
        cm = new SqlCommand(k, cn);
        cm.ExecuteNonQuery();
        Response.Write("Data saved");

    }