Thanks for your very kind replies guys.
Lampion, I'll certainly tell you. Firstly, I scanned the image, as you saw a while back. Then I selected the areas of Munch's skin that I wanted to make that green base colour. Once selecting it all, I altered the lightness/darkness and hues until it got that browny green colour. Then I selected the painbrush tool and layered out the lighter and darker shadows on the skin until it looked right. I got the smudge tool and blended the colours together to make him appear smooth. I used similar techniques to do the basic eyes. Then I drew the dots all over his body, then used a soft brush to show light on them. I used the airbrush tool to do the light in his eyes, and the airbrush for the background *Phew*
Thanks Middlesboogie.

Like Lampion said, Photoshop is really expensive, but you could try the trial version. Or you could illegally download it from the net (not that I advise that..) If you know somebody who has the program they could lend you the disc and you could install it on your machine. That would be illegal, of course, but you get what I'm saying.