In a word - You Can't !
You can only embed an image that apears somewhere else on the web (using the "IMG" UBB tags_
If you have your own web site, you could upload the image to your own web site and use the IMG tag to point to it. Alternatively, you could get someone else to put it on their web site (I heard there's someone on another section of the board who kindly does this, but not sure who)
And Danny has the IMG tag disabled in one or more sections of the board (I think Jet Blast does not allow it) to conserve his server processing time and to make people's download of pages faster.
No - not a dumb question at all!
------------------
What goes around . . .
. . often lands better!