It's "Tormod", not "tormor".
All you need to do is to use some kind of photo editing software (like Paint Shop Pro, from
http://www.jasc.com/.) Scan a photo or use a digital camera.
Crop the image so that it basically shows your head (!) and set the width and height to a maximum of 100 pixels. Then export it as a JPG image. The file size must not exceed 30 Kilobytes, but I recommend trying to get it down to 3-4K at most. What I did was to desaturate my photo (which means "removed the color" in English) and then apply some color with the colorization feature (often called "hue/saturation"). The fewer colors the smaller the filesize (usually).
When you're done, go to your profile page like when you added the signature. There is a field for "Upload your own user icon" (or something like it).
Tormod