How to replicate this select box?

How to replicate this select box?

Hi.  Stumbled on this select box which I believe uses jQuery:

I would like to know how to replicate it.  I can see that there are background images and the search button is an image, but it's the size of the fields and the coloured dropdown background that I really want to understand.  I'd also like to add an input field above the select boxes.

Any ideas how to achieve this?  Thanks in advance.

Veronique