Use the MenuBar.DisplayMode property to determine the layout of the MenuBar object. To make a horizontal MenuBar, set:
On order to make the horizontal MenuBar position itself relatively on the page, set the MenuBar.AbsoluteDockEnabled and MenuBar.AbsoluteDragEnabled properties to false.
The MenuBar will now be rendered at the location on the page where you have placed the WebMenu code. The MenuBar's width is 100% and will stretch to fit its parent container's width.