add descendants as submenu – hover problem

hej,

it´s my first try to “redesign” a wordpress website. And I wanted to integrate a sub-menu. I would like to have a hover over the menu item “kurse” so that the sub-menu becomes visible. But I didn´t figure out how to do that… Is it possible!? Any ideas!?

would be very happy about some help! 🙂

link to the site:
http://pralinen-schule.de/