Oops. My fault. It was late when I did that and I thought
your title said center.
When you first try to insert the menu it should give you the
option for both.
If you choose the wrong way there are 2 ways to fix this. The
first is to just delete the original menu and create a new one. Or
the quick fix is to do this:
In the code view you will see a class defined at the
beginning of your menu "MenuBarVertical" will be the class. Then
head over to the Adobe labs and from their samples you can find the
address of their CSS and you end up with this:
http://labs.adobe.com/technologies/spry/widgets/menubar/SpryMenuBarHor izontal.css
Save that file into the SpryAssets folder. Change the
previously mentioned MenuBarVertical to MenuBarHorizontal and
changed the linked CSS document from SpryMenuBarVertical.css to
SpryMenuBarHorizontal.css. Then re-upload the file and upload the
new CSS document and you are good to go.
Btw the homepage to the Spry page of the Adobe labs is:
http://labs.adobe.com/technologies/spry/home.html
There is also a link to the official Spry forums should you
need further assistance. But if you do that I would recommend
downloading the Spry Updater. All you have to do is download the
zip file and inside you will find a Dreamweaver extension. Install
the extension and everything will be updated.