I just thought that I would add some information here that might be helpful to others since the OP's instructions raised questions that didn't seem to be addressed and hardly anyone has posted any pictures since .... so ....
I use a free off-site image hosting site called "Tiny Pic". It will allow you to upload an image and then copy and paste the URL here to display photos like mine above. Once you do it a couple times, it's super easy. Note: just ignore all ads that display and don't click anything other than what is desrcribed below:
1) Click "Browse" to locate your image on your PC (I alway use .jpg and not sure what other formats it supports). In the Explorer screen, select your image then click "Open" at the lower right. You will now see your file name in the window next to "Browse". NOTE:
I just discovered that if you use Explorer it will display "Browse" ... if you use Google, it will display "Choose File" ... either way, it's still basically the same. Also, be patient ... really large files can take a minute.
2) Click on "Resize" which opens a dropdown box of various sizes to display. My photos are usually between 1 and 2.5 Mb so I usually select the largest ... 17" screen 1024 x 768. If you photos are smaller, you might pick a smaller size.
3) Click the big green button "Upload Now".
4) A security screen will come up. Click "Play" which will usually run a short ad video (or not) but it will display a specific phrase that you need to type in where it says "Your Answer". It is case sensitive. Click "Upload Now" again below after typing in the phrase. The upload time is dependant on the size of your photo and your PC and your internet connection ... be patient. Just before it's ready, it will display "Click here to view" .... Ignore that !
5) A list of various URLs will display immediately after you see "Click to view". Select the bottom option "Direct links for layouts". Click on the URL to highlight it, then right click to "Copy"
6) On the FF forum message body, click on "IMG" from the tools at the top then paste the URL you copied from TinyPic. Then click "IMG" from the top again to bracket the URL you pasted. Then click Enter on your keyboard to go down a line (I just do this to ensure completion).
7) Click "Submit" at the bottom and wait .... be patient
On TinyPic, click "Upload More" to add more photos ... just repeat the process. Sometimes if you do this right away, it will skip the security screen and just upload the next chosen picture. If you are posting more than one picture, wait until you're finished before you do Number 7.