Protected Sub DropDownList1_SelectedIndexChanged(ByVal sender As Object, _
              ByVal e As System.EventArgs) _
              Handles DropDownList1.SelectedIndexChanged
    Dim id As String
    id = DropDownList1.SelectedItem.ToString()
    Response.Redirect("~/Admin/Accounting/Ledger.aspx?id=" + id)
End Sub

Protected Sub Page_Load(sender As Object, e As EventArgs) ...
   If Not IsPostBack Then
      DropDownList1.DataSource = DATASOURCE
      DropDownList1.DataBind()
   End If
End Sub