how to apply pagination for the grid

    protected void Page_Load(object sender, EventArgs e)
    {
//set your grid page size  propriety 
        GridView1.PageSize = 100;
    }

  protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        GridView1.PageIndex = e.NewPageIndex;
//then you have to Rebind DataGrid again 
        SqlConnection con = new SqlConnection(@"Data Source=.;Initial Catalog=test;Integrated Security=True");
        string statment = "select item_code, Item_name, brand, size, section, price, Material, Qty, tax, tt  from Items ";
        SqlDataAdapter da = new SqlDataAdapter(statment, con);
        DataSet ds = new DataSet();
        da.Fill(ds);
        GridView1.DataSource = ds.Tables[0];
        GridView1.DataBind();
    }