<script runat="server">
sub Page_Load
if Not Page.IsPostBack then
   dim mycountries=New SortedList
   mycountries.Add("N","Norway")
   mycountries.Add("S","Sweden")
   mycountries.Add("F","France")
   mycountries.Add("I","Italy")
   rb.DataSource=mycountries
   rb.DataValueField="Key"
   rb.DataTextField="Value"
   rb.DataBind()
end if
end sub

sub displayMessage(s as Object,e As EventArgs)
lbl1.text="Your favorite country is: " & rb.SelectedItem.Text
end sub
</script>

<!DOCTYPE html>
<html>
<body>

<form runat="server">
<asp:RadioButtonList id="rb" runat="server"
AutoPostBack="True" onSelectedIndexChanged="displayMessage" />
<p><asp:label id="lbl1" runat="server" /></p>
</form>

</body>
</html>