VS 2013 Express Menu click event

I have the following menu control on my master page:
<asp:Menu ID="NavigationMenu" runat="server" CssClass="menu" EnableViewState="false" Orientation="Horizontal"                   StaticMenuItemStyle-HorizontalPadding="30px" OnMenuItemClick="NavigationMenu_MenuItemClick">    <Items>         <asp:MenuItem NavigateUrl="~/Default.aspx" Text="Home" Value="1"></asp:MenuItem>         <asp:MenuItem NavigateUrl="~/Forums.aspx" Text="Forums" Value="2"></asp:MenuItem>    </Items> < ...