on mouse over a window pops up
how can i do this
I can tell you that it's not a window. It's script generated HTML markup made to look like a window.
It's a sort of Lightbox, or more generically, a modal window of sorts. There are tons of Lightbox and Lightbox type scripts around and also plenty of modal window scripts. To make any of them that I know of look and act just like the one on that page would require tweaking, probably fairly extensive tweaking. Most if not all of them use onclick, changing to mouseover would be easier for some than for others. ColorBox:
might be one that is most easily adapted because, according to the documentation, you may load one up with an event of your choosing.