<link rel="shortcut icon"
href="http://someWebsiteLocation/images/imageName.ico">
If i may add more clarity for those of you that are still confused. The .ico file tends to provide more transparency than the .png, which is why i recommend converting your image here as mentioned above: http://www.favicomatic.com/done also, inside the href is just the location of the image, it can be any server location, remember to add the http:// in front, otherwise it won't work.