Align menu subitems in the center

Hi all,

I have been playing with my joomla submenu items for quite a long time but i am not an expert in CSS at all, expecially with Joomla and artisteer (template generator)

So what I would like to do is get the menu subitems to be centered, and if possible with a separator.

Could anyone help me with these last steps of my work on that menu?

Thank you so much

http://www.laplanchette.com.au/test/