Lauren Blake Proffitt- StumbleUpon- painting an eye

I am an amateur painter and one area I find myself lacking in artistically is painting humans. I also have a deep love for eyes and the stories they tell. This website is extremely interesting to me because I would love to know how to paint anything better and this showes me one of my favorite things. I suggest this site to anyone in my situation of artistry. The site is not cited at all but I do not believe this is a call for one. My question is; is there a certain type of paint that was used in this tutorial or will any type work?