How to realise a dropdown chained lists?

Hello,
I read the article to realise a Country List but I wish to know how to do to realise chained list of this type:

regions
---province

---

cities

How I can to chain each list?

Thanks.

Somebody wants help me?
I wish to collaborate with your CB community but if nobody helps replies me, how I must to do realise some additionals plugins?

I have a big Database, divided in Continents, Nations, Regions, Provinces, Cities.
I think a plugin of this genre is very appreciated by every user who choose Community Builder as base to build a community.

I hope somebody replies to me.

Only solution I can suggest it the CB Conditional plugin - one of our Incubator projects.

Its available to professional members.

A short review with a video to see this in action is located here:
www.joomlapolis.com/cb-conditional-short-review

--
Sorry for the delay in responding. The CB Team monitors free forum areas but we focus on Advanced/Professional areas on a priority basis and look at other areas as time permits.

Sorry,
but I think I was not clear.
I know how to chain more dropdown fields (with javascript) but I do not know How to do that in CB.
For this reason I ask a little help to realise that under CB.
I would be fine too a little tutorial to know how realise a CB plugin of medium complexity.

I would to help CB community to increase, but you help me please!

I created a wonderful CB plugin that allows to search all world cities by input the city name and to choose the city by autocomplete.
In the registration page every body can choose their city.
It works with CB 1.2, 1.3 and 1.4