Adding a triangle below Top Level Menu when hovered

Hi
I have just purchased the menu and I am testing it out for a client
They want the little triangle below top menu element to show when hovered.
You can see an example what I mean here: www.humana.org/

I have searched up and down on Google but I am not able to find a solution that works, probably because i dont know what classes i should add the CSS to to get this outcome

Thanks
Morten

Hi
Thanks for your reply?
I am getting grey hair finding the right classes as I cant find any that I can use

How much would it cost to make it and provide me with the CSS code so i can further customize it if customer want to change color, size etc?

regards
Morten