Hey Ron,
Here is a tutorial on posting photos, they have to be hosted at another site.
http://pickelhaubes.com/forum/viewtopic.php?t=4690
I suspect that photos can be posted on a signature using the same method, but I would caution puttin any large photos on a signature, as it slows the loading process for those who do not hve high speed internet service (this may be less of a problem now) and it tends to clutter up a thread with unrelated photos, especially if the poster makes several posts to a thread.
Best
Gus