Hello Horst Fuchs,
I have help you configured the group and profile submenu item regarding this.
STEP 1 : Create a submenu in your "main menu" > Home(Easysocial)
STEP 2 : Create menu item alias for you group and profile under > Submenu
STEP 3 : Create a menu module link to your Easysocial menu item and display on "submenu" position
by the way, you can read more in our documentation :
http://wanderers.stackideas.com/documentation/creating-sub-menu
Hope this help.