There isn't any Start menu in Office; Open is a command under the
Office button (top left) of Word2007, and either already is on or can
easily be added to the Quick Access Toolbar.
Ctrl + O also displays the Open dialog box. Ctrl + N will open a new
blank document. Keyboard shortcuts are much faster than grabbing for
the mouse to click on icons.
If you are referring to the Start menu in Windows, you can do the following:
Right-click the Start button on the taskbar. From the context menu, choose
Open. Add a shortcut to the desired folder; the shortcut will then be
available when you click the Start button.