gridview row command event on button click

protected void GridView1_SelectedIndexChanged(object sender,
EventArgs e)
{
// Get the currently selected row using the SelectedRow
property.
GridViewRow row = GridView1.SelectedRow;
TextBox2.Text = row.Cells[2].Text;

Response.Redirect("NextPage.aspx?User=" + row.Cells[0].Text + "&Address=" +  row.Cells[1].Text;
}