Create your menu using "Add button" and "Add submenu's item's buttons.
Use various ready to use Templates. Double click on the Template to apply it.
Change button appearance for normal and mouse over states and set buttons/submenus link properties and link target attributes.
Save your menu as project file, as HTML page or insert your menu into the existing HTML page
CSS HORIZONTAL FLYOUT MENU
Let's assign text to the subitems. Select first item in the submenu by clicking it and then enter text in the "Text" field on the Properties toolbox. You will see that, as you enter the text, the selected submenu's text will change too.
Then select next item in the submenu with click. Enter its text and so on. After finishing, the menu will look like this:
Let's change the submenu theme. To do it just select theme you like in the submenus themes list on the Themes toolbox. Then you can browse this theme's submenu backgrounds. Note, that submenu backgrounds are previewable. You can look at their behavior while choosing. Just point mouse at it to know how submenu will react.
When you find a submenu background you like, double-click it to apply. For example, after choosing one of the "blue" theme's backgrounds, we'll get following results:
Submenus drop down over all the objects of the page (select, flash, object, embed).
Each change of button-menu appearance is instantly displayed in the Preview Window.
At the same time, you will be able to test how the buttons would respond to the mouse events.