In order to insert a new menu you have to:

• Ensure that the Macromedia Dreamweaver is in Design mode or in the Design portion of the window in Split mode.
• Ensure that no existing menus are selected. You cannot insert a new menu inside another menu.
• Click the New button in the DHTML Menu Extension floating window
  Click or drag the Insertbar DHTML Menu icon
  or
  Choose Insert > DHTML Menu from the main menu

If the document is unsaved you will be prompted to save it before continuing.

• Create your menu in the DHTML Menu Extension and confirm insertion by clicking Done button.

For more information about menu creation refer to the Building the menu section.