How to get Curvy Corners working?

Hi,

I'm using drupal 6.x with the marinelli theme.
I want to curve the tops of the primary links, like tabs.

I've installed the Jquery plugin and de curvy corners plugin, and activated it.

But what kind of lines should I put in the textbox below in drupal?
I want to apply it to all pages

This is the ID: #utilities #plinks ul li a

I've tried this, but it does nothing.

$("#utilities #plinks ul li a ").corner("round top");

Please help,

Thanks in advance!

Maurice