You can access to template manager with the top menu : "Extensions --> Template Manager --> minimalist "
With "minimalist template", you can :
It's very simple. Only one position for your nav main :
For obtain this, the parent item must be a link (for article or component) or a "separator item".
With this menu, you can display only one level of sub menu.
If you want change the background of tooltips, change the "bubble.png" in images directory of this template.