is it possible, when making a text area... like this
http://www.lissaexplains.com/html5.shtml#textarea
to change the scrollbar colors?

It is. Just look at the CSS section (http://www.lissaexplains.com/css.shtml) and the portion you need to change the scrollbar is on there. However, it only works for Internet Explorer, so if you're using Firefox, Opera or another browser, you won't see it. :)

Thank you!! :D

You're welcome. :)