Drop down created from backend ,how to get selcted value in backend

Drop down created from backend ,how to get selcted value in backendwhen value is changed in dropdown menu
code to create dropdown menu from backend
vb.net code:
if Not IsPostBack Then
MultiView1.SetActiveView(View1)
Dim ds As DataSet = ALMenu.GetDataMenuList()
Dim ctrl As DropDownList = New DropDownList()
ctrl.ID = "MenuField1"
ctrl.AutoPostBack = "True"

For R = 0 To ds.Tables(0).Rows.Count - 1
Dim i As ListItem = New ListItem(ds.Tables(0).Rows(R).Item(1))
ctrl.Items.Add(i)
MenuItemsCategory.Controls.Add(ctrl)
Next
End If
Protected Sub MenuField1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
Response.Write("selected index")
 Dim SelectedCategory As String = MenuField1.SelectedValue

End Sub
asp.net code 
<asp:Label ID="lblMenuDropDown" class="lbl" runat="server" Text="Menu Category"></asp:Labe ...