<asp:Menu ID="Menu1" runat="server" StaticDisplayLevels="3">
  <Items>
    <asp:MenuItem Text="File" Value="File">
      <asp:MenuItem Text="New" Value="New"></asp:MenuItem>
      <asp:MenuItem Text="Open" Value="Open"></asp:MenuItem>
    </asp:MenuItem>
    <asp:MenuItem Text="Edit" Value="Edit">
      <asp:MenuItem Text="Copy" Value="Copy"></asp:MenuItem>
      <asp:MenuItem Text="Paste" Value="Paste"></asp:MenuItem>
    </asp:MenuItem>
    <asp:MenuItem Text="View" Value="View">
      <asp:MenuItem Text="Normal" Value="Normal"></asp:MenuItem>
      <asp:MenuItem Text="Preview" Value="Preview"></asp:MenuItem>
    </asp:MenuItem>
  </Items>
</asp:Menu>
Appearance and Behavior
You can adjust the behavior of the Menu
control through its properties. Additionally, you can control the
behavior of dynamic display, including the amount of time a menu node
remains visible once it is displayed. For example, to change the Menu orientation from horizontal to vertical, you can set the http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.menu.orientation%28v=VS.80%29.aspx property as follows:
[Visual Basic]
Menu.Orientation = Orientation.Vertical
[C#]
Menu.Orientation = Orientation.Vertical;
Setting the property to Orientation.Horizontal changes the orientation back to horizontal.
You can set individual properties of the Menu
control to specify the size, color, font, and other characteristics of
its appearance. In addition, you can apply skins and themes to the Menu control.
Style
Each
menu level supports style properties. If no dynamic style properties
are set, the static style properties are used. If dynamic style
properties are set and no static style properties are set, the default
rendering of static style properties is used. The Menu control style hierarchy is as follows:
Control
SubMenuStyles
MenuItemStyles
SelectedItemStyles
HoverMenuItemStyles
These styles are merged across dynamic and static menus by using the following logic:
Each individual style is applied to the appropriate action or item type.
All styles are a merged into the style preceding them in the hierarchy, with the last style overriding.
For more Information please refers the following site
http://msdn.microsoft.com/en-us/library/ecs0x9w5(VS.80).aspx
Best Regards :)