How to detect a clicked hexagon on a hexagon tiled game board

Hi, I like to have a game on a gameboard that is build up of hexagons. In the beginning al hexagons are blue, if a user clicks one it should turn yellow. Does anyone have an idea how I can detect which hexagon is clicked on the gameboard (and what the best way is for building this map)?

You might want to read these:

http://www.gamedev.net/reference/articles/article747.asp
http://www.gamedev.net/reference/articles/article748.asp

and look at this section:

http://www.gamedev.net/reference/list.asp?categoryid=44

The articles are all in C/C++ but the theory is exactly the same and the code fairly straightforward and easily convertible to VB.

Thanks a lot, I start reading today.