How do you get a photo in your signature area?

[Mokona]

I know this is probably not the right place to ask, but I'm not sure where else to ask it.

I have my image, and I wrapped it in [img] and [/img], and all that comes up is a hyperlink. I can't get the picture to show like so many of you have.

Can you tell me what I'm doing wrong? Thank you!