<script runat="server">
Sub submit(sender As Object, e As EventArgs)
   label1.Text="You selected " & radiolist1.SelectedItem.Text
End Sub
</script>

<!DOCTYPE html>
<html>
<body>

<form runat="server">
<asp:RadioButtonList id="radiolist1" runat="server">
   <asp:ListItem selected="true">Item 1</asp:ListItem>
   <asp:ListItem>Item 2</asp:ListItem>
   <asp:ListItem>Item 3</asp:ListItem>
   <asp:ListItem>Item 4</asp:ListItem>
</asp:RadioButtonList>
<br>
<asp:Button text="Submit" OnClick="submit" runat="server"/>
<p><asp:Label id="Label1" runat="server"/></p>
</form>

</body>
</html>