Wrong place to ask this question. I can try to answer your questions in the help thread next time though.
Ehhh lets see.
If this picture is on your desktop I want you to upload it to a photo sharing website like "******* or photobucket". From there I want you to copy the image url. Now come back to mpgh and copy and paste that image url into the signature field located "user cp>edit signature". When that is done put image quotes around the url pasted.
So it should look like this:
[IMG]"Url goes here with no spaces in between the IMG's and url"[/IMG]